P0299 Code: Turbo Underboost Meaning, Causes and Fix

A P0299 code is the OBD-II diagnostic trouble code, or DTC, for turbo underboost: your engine made less boost, the extra air pressure a turbo pushes in, than its computer asked for. You meet it as a check engine light, a car that won't pull, or both.

Its full name is Turbocharger/Supercharger A Underboost Condition, from the code standard Europe's EOBD also follows, and the P0299 error code is often typed PO299 with a letter O, or P299. Audi's bulletins write it P029900, Ram's P0299-00 and Ford's P0299:00, the same code with a suffix, so a Ford reading of P0299:00-EC is still P0299.

Below is what sets it on your engine, whether you can drive on it, which repairs are free, and what the parts cost on ten of the turbo cars drivers ask about most. It comes from 60 carmaker documents and the 147 federal complaints that name the code.

What does P0299 mean?

It means the boost pressure sensor read less pressure than the engine computer wanted, for long enough that the computer stored a fault. GM's own test compares exactly those two readings, and on a healthy turbo the measured line closely tracks the one the computer asked for.

Underboost is a shortfall, not a verdict on the turbo. The wastegate, a valve that lets exhaust bypass the turbo to limit boost, can cause it by opening when it shouldn't.

So can air leaking out after the turbo, or an intake starved of air, and each gives the same low reading.

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The code covers superchargers too, which are driven by a belt instead of exhaust. Every car in this article is a turbo, because that's where the complaints and bulletins are.

What you notice varies with how big the shortfall is, and the symptoms of a P0299 code come in five kinds:

• A check engine lightSometimes the only sign, because a small shortfall may not be something you can feel.
• Reduced power or limp modeLimp mode is the computer capping power to protect the engine. 51 of the 147 complaints describe losing power, and GM cars may show engine power reduced on the dash. Owners describe it when the engine works hardest: 15 complaints mention merging or an on-ramp, and 13 a hill.
• Hesitation in hard coldGM's bulletins describe power loss, hesitation and stalling at 0°F or colder that fade as the car keeps running.
• A new rattle from the turboGM's Encore GX and Trailblazer and Ford's F-150 documents tie a rattle to worn or loose wastegate parts, one cause of a rattling noise when accelerating.
• A louder turbo, or smokeGarrett, a turbo maker, says a turbo failing from oil trouble gets sharply louder and leaks oil past its seals, which burns and shows as exhaust smoke. Both are reasons to stop, below.

What causes a P0299 code?

A leak in the air path, winter ice, a wastegate part or a clogged filter, before the turbo itself. GM's bulletin for the 1.4 turbo opens with the cases where a turbo that set P0299 should not be replaced, the first a cracked wastegate port it calls normal.

GM wrote that bulletin because good turbos kept coming back from repairs with nothing wrong, the parts-counter version of blaming the dog. Across the makers' documents, the other codes stored with your P0299 point to which cause set it:

Other guides list causes that the bulletins treat differently, and these six P0299 causes each need a caveat.

1. Low oil supply to the turbo

Engine oil lubricates and cools the turbo, which Honda's Accord manual says spins above 100,000 rpm at over 1,292°F. Starve it of oil and its bearings fail, Ford warns, and Garrett, a turbo maker, lists worn bearings among the causes of lost power.

Garrett puts more than 90% of turbo failures down to oil, and under 1% to how the turbo was made. So if a shop says your turbo failed, ask what failed it: GM checks the oil feed pipe with a new one, and Ford replaces its oil filter (SSM 47662).

2. Boost sensor

The boost sensor reads the pressure the turbo builds, and P0299 means that reading fell short of what the computer asked for. GM says ice on the sensor can set the code in hard cold (PIP5495N).

A failing sensor or its wiring sets its own code in the bulletins we read: Ford's cracked-wire bulletin and Honda's name P0236, not P0299 (TSB 13-6-12, A21-049). Ask for GM's boost test before you buy one, because a 2014 Cruze owner replaced the sensor, then the solenoid, and the code came back both times.

3. EGR or a diesel filter

On a diesel, the EGR valve feeds some exhaust back into the intake to cut emissions, and the particulate filter traps soot before the tailpipe. Ram's P0299 checklist for the 6.7 Cummins includes a leaking or shifted EGR valve and a plugged particulate filter (STAR S2018000007).

The same checklist ends with a test of the turbo's variable vanes, and only a failed test means a new turbo. None of the carmaker documents we read names the EGR valve for P0299 on a gas turbo.

4. Restricted exhaust

Exhaust spins the turbo on its way out, and exhaust that can't get out fast enough, called backpressure, can set P0299 on a healthy turbo. GM lists excessive backpressure among its reasons not to replace a turbo that set the code (PIP5495N).

A clogged catalytic converter is one source, and Garrett tells shops to check the converter and a diesel's particulate filter when a turbo engine lacks power. Our guide to bad catalytic converter symptoms shows the signs of a clogged one.

5. PCV valve

The PCV system vents fumes from inside the engine back into the intake. GM's cold-weather bulletin for the 1.4 turbo names ice in those vent hoses as a cause of P0299 at 0°F or colder (16-NA-405).

Outside the cold, GM's coverages for a failed PCV valve in the 1.4's cam cover name P0171, a lean code, not P0299 (N202299080, N192210230). So in mild weather a PCV repair answers P0171, and P0299 still needs the leak and boost tests.

6. Cam or crank codes

A cam or crank code, such as P0016, means the computer sees the camshaft and crankshaft out of step, which can mean the valves open at the wrong time. Garrett's turbo troubleshooting chart lists valve timing among the causes of lost power that aren't the turbo.

11 of the 147 complaints list one with P0299, and 9 of those describe a failing engine, from stretched timing chains to low oil pressure. So if you have one stored, have the engine checked before anyone replaces your turbo.

Is it safe to drive with a P0299 code?

For a short, gentle drive to a shop, yes, as long as none of the stop signs below shows. GM's 2014 Cruze manual says you may drive at a reduced speed when power is cut, and should see a dealer soon if the message stays on.

Stop as soon as it's safe, and don't drive on, if you see any of these:

• The oil pressure warningGM's Cruze manual says to stop and not drive again until the cause is fixed, and Honda's Accord manual says to park at once.
• An overheating warningHonda says to park somewhere safe and let the engine cool, and GM says not to keep the engine running if its cooling fan isn't.
• A light that keeps flashingFor a flashing check engine light, GM says to slow down and avoid hard acceleration and steep hills, then stop and restart. If it blinks again after a restart, Honda allows 31 mph or less to the nearest dealer.
• A grinding or siren noise, or smokeGarrett ties a sharply louder turbo and burned oil to a turbo that's failing. We'd have the car towed rather than drive it.

Owners who gave a speed describe a car that still moves but won't keep up: 22 complaints give one, and 11 the speed the car was held to, from 5 to 60 mph. 7 of those 11 fall between 30 and 45 mph, fine for a side street and less fine for a merge lane.

Why does P0299 come back in cold weather?

Because moisture from the engine can freeze in the intercooler or the wastegate solenoid of GM's 1.4 and 1.5 turbos at 0°F or colder. GM's bulletins say the power loss fades after the car has run for a while, which is why your code seems to come and go all winter.

Winter already takes your daylight and your patience, and on these engines it takes your boost too. The same bulletins still tell technicians to rule out leaks first, because some moisture in the intercooler is normal and proves nothing.

GM's fix depends on the engine, and each P0299 cold-weather fix below names its bulletin:

• A winter grille coverIt keeps the intercooler warmer. GM says to remove it once temperatures stay above 32°F, and before towing any trailer (16-NA-405).
• A revised intercoolerOn 2013 to 2022 Encore and Trax and on 2016 to 2019 Cruze 1.4 that haven't had one (16-NA-405, 17-NA-221, 22-NA-007).
• A drained wastegate solenoidBlown clear and wrapped against the cold, or replaced if its plunger has hardened deposits (PIP5812C, 22-NA-007).
• New engine softwareOn the 2016 to 2019 Cruze it uses overdrive less in the cold, so expect higher highway rpm. GM covers the update for 8 years or 80,000 miles (22-NA-007).

P0299 by car make and model

P0299 means the same shortfall on every turbo car, but the part behind it follows the engine, and each maker writes its own fix. We cover these makes because they're behind 129 of the 147 federal complaints that name the code, and the models within them are the ones drivers ask about most:

Jump to your car: Cruze, Trax and Encore, Equinox, Malibu and Terrain, Ford F-150 and Escape, or Ram, Audi, Honda and others.

The numbers in parentheses are the makers' own documents: technical service bulletins, and the shorter technician notes GM calls PIPs, Ford calls SSMs or ASIs and FCA calls STARs.

Chevy Cruze, Trax and Buick Encore (1.4 turbo)

On the 1.4 turbo, GM's documents name a wastegate part, a leak or winter ice, and on some 2017 and 2018 cars a turbo that GM replaces free. Here's what causes P0299 on your Chevy Cruze, Trax or Encore, oldest first:

• 2011 and 2012 Cruze, original turboThe wastegate losing its preload, the tension that holds it shut; some wear at its pin is normal and sets no code. GM checks the retention clip, then wiggles the wastegate lever by hand. If the lever moves easily while the actuator rod stays still, it replaces the turbo (PI1366, PIP5495N).
• 2011 to 2016 Cruze, 2012 to 2020 Sonic, 2013 to 2020 Encore and TraxA leak, a restricted air intake, a wastegate part or the bypass valve, which GM checks first. It replaces the turbo only after its boost test, the last of the fix steps (PIP5495N).
• 2013 to 2022 Encore and Trax, 2016 to 2019 CruzeIce in the intercooler or wastegate solenoid at 0°F or colder (16-NA-405, 17-NA-221, 22-NA-007).
• 2017 and 2018 Encore, Trax and SonicThe turbo itself can fail. GM replaces it free for 10 years or 120,000 miles from first service, when its diagnosis leads to the turbo. That's special coverage N232395330, a free repair GM offers outside a recall.

Among single models, the Encore has the most complaints naming P0299:

A 2016 Encore owner was told the turbo coverage applied, though its document lists only 2017 and 2018. So have the dealer check your VIN, not the model year.

Chevy Equinox, Malibu and GMC Terrain (1.5 turbo)

On the 1.5 turbo, four GM documents name the intercooler tube coming off the throttle body, and the other codes stored with it give that away. Here's what causes P0299 on your Chevy Equinox, Malibu or GMC Terrain, oldest first:

• 2016 to 2018 MalibuA broken wastegate actuator rod. GM replaces the actuator alone and says a whole turbo isn't recommended (PIP5539). Ice at 0°F or colder is the other cause (18-NA-069).
• 2018 to 2022 Equinox, 2020 to 2022 Malibu and TerrainThe intercooler tube off the throttle body, with P0101, P1101, P0172 or P0506 stored too. Pushed back on or held with a retainer kit, 0.3 to 0.4 hours of GM labor (PIP5710A, 22-NA-224).
• 2019 Equinox, Malibu and TerrainThe same tube, in an emission recall, made for an emissions fault rather than a safety defect. It's free if still open on your VIN (N192271200).
• 2018 to 2024 Equinox and TerrainMoisture freezing in the intercooler at 0°F or colder (18-NA-020), and on some a frozen wastegate solenoid (22-NA-002).
• 2022 MalibuThe turbo itself. GM replaces it free for 15 years or 150,000 miles when its diagnosis leads there (special coverage N252508360). It repays earlier repairs claimed by November 30, 2026.
• 2023 to 2026 Equinox and TerrainA collapsed or split inlet hose, the one that feeds air into the turbo (PIP5927E).

The Malibu's complaints naming P0299 peak in 2022, with 6, the same model year as the turbo coverage. The dealer told a 2018 Equinox owner the freezing was a design flaw with no recall, and the owner put the cost at $1,100 out of pocket.

Ford F-150 and Escape (EcoBoost)

In Ford's documents it's the wastegate: its control solenoid on the Escape 1.6, its actuator rod or clip on newer engines. Here's what causes P0299 on your Ford F-150 or Escape in Ford's documents, oldest first:

• 2011 to 2014 F-150 3.5We found no Ford document naming P0299. On 2011 to 2013 trucks, an intercooler moisture problem sets misfire codes instead, P0304 to P0306 (ASI 32166).
• 2013 to 2016 Escape 1.6Ford checks the intercooler tubes and vacuum lines first, then replaces the wastegate solenoid, 0.6 hours of labor (TSB 15-0162). The 2013 and 2014 Fusion and 2014 to 2016 Fiesta ST share the engine and the bulletin.
• 2020 to 2022 Escape 2.0An inoperative wastegate actuator, a missing clip or a damaged actuator rod. Ford sells the actuator, rod and clips as one kit instead of a whole turbo (SSM 50485). The 2019 to 2022 Edge and 2021 to 2022 Bronco Sport share the fix.
• 2021 F-150 3.5 PowerBoost, built by September 30, 2021A restricted outlet pipe on the right air cleaner, with P0301 to P0303 stored too and sometimes blue smoke. Ford replaces the pipe, and says the restriction can damage the right turbo (TSB 22-2017, 24-2257).
• 2021 to 2025 F-150 3.5A disconnected wastegate actuator rod, sometimes with a rattle. Ford now supplies the rod, springs and clips separately (SSM 54392).
• 2024 F-150 3.5 PowerBoostThe upper air deflector can deform and choke the air to the right turbo, which then overspeeds and can be damaged. Ford replaces the deflector (TSB 24-2264).

On 2010 to 2019 Ford turbos, the turbo's oil supply filter must be replaced whenever the turbo is (SSM 47662). We didn't read Ford's Power Stroke diesel documents.

Ram, Audi, Honda and other makes

Outside GM and Ford, Ram, Audi and Honda come up most in the complaints, and each make has its own P0299 document, or none:

• Ram 2500 and 3500, 6.7 Cummins dieselFCA's 2026 bulletin fixes P0299 on 2019 to 2024 trucks with a new air filter, and a parts notice replaces the earlier oiled one (09-003-26, GPOP 9100678). So yes, a restricted or wrong air filter can cause it, and on 2023 to 2026 trucks dealers also have a new air-handling test for it (08-272-26). On older trucks sold as the Dodge Ram, we found no bulletin naming P0299. Chrysler's 2013 bulletin for the 2010 trucks names P2262, boost pressure not detected, instead (18-005-13).
• Audi A4, A5 and Q5 2.0 turboWear in the wastegate linkage lets boost escape. The 2009 to 2012 A4 and A5 and the 2011 and 2012 Q5 got a new turbo with a new clip (2031245/7). On 2013 and 2014 cars the clip can fall off, and a new one fixes it without a turbo (2039006/3). On the 2005 to 2007 A3 and A4 2.0 TFSI, a torn membrane in the recirculation valve sets it, and a new valve fixes it (2013060/7).
• Audi Q5 and SQ5, 2020 to 2022On cars built before October 14, 2021, material can build up inside the charge-air pipe after the intercooler, so full boost never arrives. When desired and actual boost disagree and nothing else leaks, Audi fits a new pipe (01 22 21). It covers the 2020 to 2022 SQ5 and Q5 plug-in, and the 2021 and 2022 Q5 and Sportbacks.
• Volkswagen 2.0 turbo, 2008 to 2015Volkswagen's tech tip for its 2.0 TSI engines coded CCTA and CBFA names P0299, and NHTSA files it under the GTI, Jetta, Passat, Tiguan and others (TT 21-10-02). A pin in the turbo's exhaust housing backs out, so the wastegate lever and valve drop and can stick open. The check is a gap of about 3 mm under the lever, and with no gap the turbo is replaced.
• Mercedes-AMG V8, 2015 to 2020On AMG 63 models with the M157 V8, from the CLS, E, G, GL, GLE, GLS and ML to the S and SL, a leaking vacuum pump sends oil into the boost pressure transducer, and turbo pressure turns erratic, with the check engine light and a limp mode. In March 2026 Mercedes extended the emissions warranty on the transducer, the vacuum pump and its lines to 15 years or 150,000 miles, and offered to repay earlier repairs. We found no Mercedes document naming P0299 on its four-cylinder cars.
• Hyundai and Kia turbosHyundai's campaigns for the 2015 Veloster Turbo and Sonata 1.6 turbo name P0299 and a restriction in the intercooler's pressure port, but both were for cars still in dealer stock, so an owner can't claim them (15-01-006, 14-01-045). Kia's service action for 94 Stinger 2.0 turbos built in October 2020 names poor oil flow to the turbo, and a dealer can still do it under warranty (ENG 223).
• Honda Accord 1.5 turboWe found no Honda bulletin naming P0299 on the 2018 to 2022 Accord or CR-V. Eight Accord complaints name it, one describing play in the wastegate rod.

Mercedes, Hyundai and Volkswagen appear in two or fewer complaints each, so their documents above are the better guide. 5 of Land Rover's 6 are the Discovery Sport or the Range Rover Evoque, and we didn't read Land Rover's documents.

Is there a recall for P0299?

No safety recall names P0299 or turbo underboost on the models we checked. The free repairs come as special coverages, an emission recall and a service update, and your recall search won't show any of them:

A special coverage isn't a recall, and it pays only when the dealer's diagnosis leads to the covered part. Its clock starts the day your car was first put in service, so a 2017 sold new in 2016 counts its 10 years from 2016.

The 2017 and 2018 coverage's deadline for repaying earlier repairs passed on March 31, 2025. A 2022 Malibu owner was told the VIN was excluded, but the coverage goes by VIN, so ask the dealer to check your VIN.

Does your warranty cover the turbo?

Outside those, your powertrain warranty may pay for the turbo itself, and the makers' booklets differ:

• Chevrolet, GMC and Buick, 5 years or 60,000 milesThe powertrain list names the turbocharger but leaves out sensors and wiring, so a failed boost sensor isn't covered by it.
• Ford, 5 years or 60,000 milesThe powertrain list names the turbocharger unit. Ford's diesels get 5 years or 100,000 miles, with the turbo actuator named too.
• Ram, 5 years or 60,000 milesThe gas engines' list names the turbo's housing and internal parts and its wastegate actuator. The 2500 and 3500 with the 6.7 Cummins get 5 years or 100,000 miles, with the turbo and all sensors named.
• Hyundai and Kia, 10 years or 100,000 milesFor the first owner, with the turbocharger named. Later owners get 5 years or 60,000 miles.
• Honda and VolkswagenHonda's powertrain list doesn't name the turbo, though it says other parts may be covered. Volkswagen has no separate powertrain warranty, so its 4-year, 50,000-mile new-car warranty covers the turbo like any other part.

The federal 8-year, 80,000-mile emissions warranty doesn't reach the turbo: it covers the catalytic converter, the engine computer and the diagnostic system, and no turbo is on its list. On cars certified to California's emissions rules, GM's and Ford's booklets, and Kia's for several models, cover the turbo for 7 years or 70,000 miles.

The booklets we read are for 2023 to 2025 cars, so check the one for your year.

How much does it cost to fix P0299?

The parts behind P0299 cost $3.10 to $1,883 at the counter, from an air filter to a diesel turbo. The box prices each part one car at a time, so you can find yours.

Labor isn't in the box, but GM's own warranty times put a number on it. At $120 to $159 an hour, a common independent-shop rate, its 0.3-hour boost test is $36 to $48 and its 2.4 to 4.6 hours for a turbo are $288 to $731.

Added together, here's what a turbo replacement comes to on four of the GM cars priced above: the turbo's counter price plus GM's hours to fit it, before the boost test.

• 2014 Cruze 1.4$561 to $903, parts and labor, with GM's 2.4 hours (PIP5495N).
• 2016 Encore 1.4$609 to $1,201, parts and labor, with 2.8 hours (PIP5495N).
• 2019 Trax 1.4$609 to $1,013, parts and labor, with 2.8 hours (PIP5495N).
• 2022 Malibu 1.5$992 to $1,308, parts and labor, with 4.6 hours, or nothing when GM's diagnosis leads to the turbo under special coverage N252508360.

We found no GM hours for the Equinox's turbo, so it isn't added up here.

How do you fix P0299 turbo underboost?

By finding the shortfall before you buy a turbo, because the turbo is the most expensive guess. To fix P0299 turbo underboost, work through the 6 steps below, in order:

1. Read every stored code. P0101 or P1101 on a 1.5 turbo points at the intercooler tube, P2227 or P00C7 in hard cold at ice, and cam or crank codes past the turbo. See our check engine light codes for the rest. Ask for the freeze frame too: the computer saves conditions such as engine speed, load, road speed and intake pressure at the moment a code sets, which shows the shop what to recreate.
2. Run the VIN with a dealer. A special coverage, an emission recall or a service update may pay for the repair, which is why this comes before you pay anyone. Our free VIN checker shows any open recall first.
3. Look for a leak or a tube off. Check that the intercooler tube is clipped onto your throttle body and the hoses aren't split or oily. A shop's smoke test, which blows visible smoke into the intake, finds the rest, and Ram's checklist also pressure-tests the intercooler.
4. Check the air filter. A restricted or wrong filter is a documented cause on the Ram 6.7, and GM lists a restricted air cleaner among the reasons not to replace a turbo.
5. Have the wastegate checked. Ask the shop to check the solenoid, its vacuum hoses, the actuator rod and clip and the bypass valve, the parts GM, Ford and Audi fix without a turbo. A good answer names which one they checked and what they found.
6. Test boost before replacing the turbo. GM's test compares desired and actual boost at full throttle. It replaces the turbo only if the gap is more than 2 psi, about a seventh of the air pressure around you. Before paying for one, ask what the shop saw: oil at the turbo's ends or play in its shaft, the signs of worn bearings Garrett lists.

Clearing the code with a scan tool turns the light off only until the computer sees the shortfall again. After the repair, ask the shop to run the boost test once more and show you desired and actual boost side by side.

When the quote arrives, our guide to reading a repair estimate shows what to check.

If the code survives the steps, each of these three P0299 situations has a next step:

• It came back after a new sensor or solenoidAsk for the boost test before the next part, and for what it showed. A shop that can't show you desired and actual boost side by side hasn't tested the turbo yet.
• It happens only below freezingAsk about GM's cold-weather bulletins by number; they're listed in the cold-weather section.
• A new turbo didn't fix itAsk what was tested before it went in, and check the tube, the filter and the wastegate parts again. If nobody can name the test, the turbo was a guess.

Once it's fixed, the turbo page of Honda's Accord manual gives two habits that protect it: change the oil and filter on schedule, and don't rev the engine or accelerate hard just after a cold start.

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Common questions

Asked most often

What does code P0299 mean?

Turbocharger or supercharger underboost: the engine computer measured less boost pressure than it asked for. It's the same code whether a scan tool shows P0299, P029900, P0299-00 or Ford's P0299:00.

Can a dirty air filter cause a P0299 code?

Yes: FCA's bulletin for the 2019 to 2024 Ram 6.7 diesel fixes P0299 with a new air filter. GM also lists a restricted air cleaner among its reasons not to replace a turbo.

Can a bad boost sensor cause P0299?

It can in hard cold: GM says ice on the sensor can set it. A failing sensor sets its own code, P0236, in the Ford and Honda bulletins we read, so ask for the boost test before replacing one.

Will P0299 clear itself?

The symptoms can fade, as GM's bulletins describe for winter icing once the engine has run a while. The cause is still there, so the code comes back under the same conditions.

Is there a P0299 recall on the Chevy Trax or Cruze?

Not a safety recall: the 2017 and 2018 Trax, Encore and Sonic 1.4 have special coverage N232395330 for the turbo, 10 years or 120,000 miles. The Cruze has cold-weather bulletins but no turbo coverage we found.

Does P0299 on a Honda Accord 2018 have a recall?

We found none, and no Honda bulletin naming P0299 on the 2018 to 2022 Accord. Honda's related bulletins cover the 2.0 turbo's intercooler and boost sensor, with other codes.

Prices are ranges compiled in September 2026 for the US market and vary by region, engine and shop rate. Prices from $10 up are rounded to the nearest dollar, so $14.13 reads as $14 and $14.52 as $15. Below $10 they're exact. This article is general information, not advice about your specific vehicle. See the disclaimer.