P0172 Code: The Searches Say Chevy, the Record Says CR-V

OilAndMiles.com - Look up a P0172 code and the make you meet most is Chevy, with Toyota third. Read the complaints American owners actually filed and you meet a Honda CR-V, over and over, from two model years.

Both are worth knowing, because each has its own cause and its own document. What this code never means on its own is which one you have.

What does a P0172 code mean?

It means fuel trim hit its limit while subtracting. The code's own name is system too rich, bank 1, and it reads the same on a European car, where the standard is called EOBD. A bank is one side of an engine's cylinders, and bank 1 is the side that holds cylinder number one: a four-cylinder has only that one, a V6 or a V8 has a second.

The computer trims the mixture continuously, and when the long term correction runs all the way to its negative stop and the exhaust still reads rich, it stores this code.

So the fault is one of two things, and the code can't tell you which:

• Delivery. Something is putting in more fuel than was asked for, and the fuel is really there in the cylinder.
• Measurement. A sensor is reporting a mixture that isn't the one in the cylinder, so the computer is correcting against a reading rather than against the engine.

The lean code is the same procedure with the arrow turned around.

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Is P0172 a Honda problem?

Yes, and it isn't close. Ninety US complaints name this code across the 2010 to 2025 model years. Sixty-five of them are Hondas, and fifty-four of those are the CR-V.

That's not a general Honda fault. It's two model years of one model, and the owners filing describe the same repair: injectors and the high pressure fuel pipe, quoted against Honda's own service bulletins, the written instructions a manufacturer sends its dealers saying what the fault is and who pays.

The same engine and the same years are the subject of our page on CR-V oil dilution, because fuel that should have burned has to go somewhere. Chevrolet owners have a different document, and it's in the section after next. All five of their filings are one model, the Equinox, which is also the most searched single model after the CR-V.

Why does P0172 arrive with misfire codes?

Because fuel that doesn't burn cleanly reads as a misfire. Across the 215 manufacturer bulletins in the federal archive that name P0172, P0300 appears beside it in 50 and P0301 in 46, with P0303 and P0304 close behind.

That pairing is worth more than either code alone. A misfire on one cylinder points at that cylinder; a rich code with misfires spread across several points at the fuel supply they share.

What are the symptoms of a P0172 code?

Unlike the EVAP codes, this one is usually felt. Owners in the complaint record describe rough idle, hesitation on acceleration, and in the worst filings a vehicle that lost power on the highway.

A smell of unburned fuel from the exhaust and black smoke under load are the other two. None of them is diagnostic on its own, and a car can store this code and drive normally for a while first.

The two worth watching for are stalling and limp mode, the state a computer drops into when it caps power to protect something. 9 of the 90 complaints describe the engine cutting out while the car was moving, across four makes, one at 4,525 miles on the highway, and 6 describe the car dropping into a reduced-power mode. Most filings describe neither.

Will a P0172 code fail an emissions test?

Yes, and it threatens more than the test. The stored code fails on its own in states that read the computer, and clearing it leaves the monitors reading not ready, which a station rejects the same way.

The larger cost comes later. Fuel that leaves the cylinder unburned is fuel the catalytic converter has to deal with, and that's the repair the national list puts at $1,511.

What does it cost to fix a P0172 code?

From under $300 to four figures, and which end depends on whether it is measurement or delivery. The three repairs a trim code most often leads to are priced on the P0171 page:

• An oxygen sensor, $287. The measurement end, and the cheapest of the three.
• A mass air flow sensor, $346. Also measurement, and the one a cleaning is often tried on before a replacement.
• A catalytic converter. What running rich long enough produces, priced above.

Injectors are the repair that page doesn't carry, and we couldn't trace a national figure for them. One CR-V owner's filing puts their out-of-warranty quote at $1,507.08, which is one invoice rather than an average, and it's the number to ask about rather than to expect.

What should you do about a P0172 code?

Find out which half you're in before anybody orders a part. The 4 steps below start with the one that costs nothing:

1. Read every code, not just this one. Misfire codes beside it point at the fuel supply rather than at one cylinder, and that changes the whole diagnosis.
2. Ask whether a bulletin covers your vehicle. Honda has filed on injector leaks causing a rich mixture, and General Motors on intake manifold leaks and on a loose pad in the air cleaner lid skewing the air reading, so the answer may already be written for your car.
3. Ask whether the reading was checked before the part. A sensor reporting a mixture richer than reality and an injector delivering more than asked for set the same code and cost very different money.
4. Ask what the converter and the plugs look like. Running rich damages the converter and fouls spark plugs, so a quote that replaces the cause without checking the consequences may be back.

What if the code comes back after the repair?

It's the most common thing owners write about this code, and the two highest ranking community threads on it are titled exactly that. Three situations, and each one narrows rather than widens:

• A part was replaced and the code returned. The repair was almost certainly the other half. If an injector was changed and the code came back, the reading is the suspect; if a sensor was changed and it came back, the fuel is.
• P0175 is there as well. That is the same finding on bank 2, so both sides are rich at once. A single injector serves a single cylinder and can't do that, which points at something both banks share: fuel pressure, or the measurement taken before the air divides. Thirteen filings in the record name both codes together, on a Dodge, a Ford, a Kia and a Lexus.
• Nothing was found at all. This is where an owner's own checks end. Fuel pressure and injector flow are measured, not inspected, and the shop either has the gauge and the flow data for your engine or it's guessing.

Ask for the fuel trim numbers themselves, at idle and held at speed. They're what the code was derived from, and a shop that will read them out to you is a shop working from the measurement rather than from the part list.

Common questions

Asked most often

What does the P0172 code mean?

The engine computer used its whole correction range taking fuel away and the mixture still read rich. It's a fuel trim code on bank 1, and it names the direction the correction ran rather than the part that caused it.

Is P0172 common on a Honda CR-V?

It dominates the record. Of 90 US complaints naming P0172, 65 are Hondas and 54 of those are CR-Vs, with 44 falling in the 2017 and 2018 model years. Owners describe injectors and the high pressure fuel pipe being replaced under Honda bulletins.

Can I drive with a P0172 code?

Usually yes, but not indefinitely. 9 of the 90 complaints describe the car stalling while it was moving, across four makes, so it's uncommon rather than typical. The steadier reason not to wait is that unburned fuel reaches the converter, turning a sensor bill into a converter bill.

What is the difference between P0171 and P0172?

The direction. P0171 means the computer ran out of room adding fuel, this one means it ran out taking fuel away, and both are bank 1. A P0175 code is the same rich finding on bank 2. The diagnosis is the same procedure with the arrow reversed.

Why do I have P0172 and misfire codes together?

Fuel that doesn't burn cleanly reads as a misfire. In the bulletin archive P0300 sits beside P0172 in 50 documents and P0301 in 46. Misfires spread across several cylinders point at the shared fuel supply rather than at one cylinder.

What causes P0172 and P0175 at the same time?

Something both banks share. P0175 is the same rich finding on bank 2, and one injector can't make two banks rich, so the cause sits before the air divides: fuel pressure, or the measurement the computer corrects against. Thirteen filings in the complaint record name both codes together.

Will a P0172 code clear itself?

The lamp can, after several drives where the trim stays inside its range. The cause doesn't. A code that clears and returns usually means a fault that only shows at certain temperatures or loads, which is harder to find than a constant one.

This page researched no prices of its own. The three national figures are for the US market and come from our P0171 page, where they're sourced and dated; the fourth is one owner's quote from a federal filing. All four vary by region, engine and shop rate. This article is general information, not advice about your specific vehicle, see the disclaimer.