Most common OBD-II check engine light codes, ranked by owner complaints

The OBD-II check engine light codes owners report most to NHTSA, ranked from the federal complaint file, with the makes and models behind each. A count of complaints, not how often a code sets on the road.

What the record shows

This ranking covers the codes we have written about so far. Across the federal file, for model years 2010 to 2025, the codes owners name most also include P1326 (460), P2111 (332), C1391 (310) and C0020 (309), and they will join this page as their own pages are written.

The most common check engine light codes, ranked

Complaints naming each code for model years 2010 to 2025, the window every code page on this site uses. The dark bar is that window; the light bar behind it is every model year since 1996, so a code whose light bar runs far past its dark one belongs mostly to older cars.

Open a code for what it means, the makes and models named most, and the codes filed beside it. The number in brackets is how many complaints name that make, model or code.

1P0302449473

The engine computer counted too many misfires in cylinder 2, meaning that one cylinder is failing to burn its fuel properly.

  • The make named most is Ford (214), then Honda (60) and Hyundai (32).
  • The Ford Escape (99) leads the models, ahead of the Ford Edge (66) and the Ford Fusion (40).
  • Owners most often filed it beside P0300 (87), then P0303 (61) and P0304 (58).

What P0302 means and what it costs

2P0300394510

The engine computer counted misfires, moments when a cylinder failed to burn its fuel, but couldn't pin them on one cylinder, so they are random or spread across several.

  • The make named most is Ford (95), then Chevrolet (63) and Honda (45).
  • The Ford Escape (36) leads the models, ahead of the Ford Fusion (20) and the Chevrolet Silverado 1500 (19).
  • Owners most often filed it beside P0304 (103), P0301 (103) and P0302 (87).

What P0300 means and what it costs

3P0303383415

The engine computer counted too many misfires in cylinder 3, meaning that one cylinder is failing to burn its fuel properly.

  • The make named most is Ford (146), then Honda (76) and Kia (37).
  • The Ford Escape (68) leads the models, ahead of the Ford Edge (39) and the Chrysler Pacifica (30).
  • Owners most often filed it beside P0300 (75), then P0302 (61) and P0301 (47).

What P0303 means and what it costs

4P0304358400

The engine computer counted too many misfires in cylinder 4, meaning that one cylinder is failing to burn its fuel properly.

  • The make named most is Ford (127), then Honda (89) and Kia (36).
  • The Ford Escape (58) leads the models, ahead of the Ford Edge (34) and the Honda Accord (21).
  • Owners most often filed it beside P0301 (103), P0300 (103) and P0302 (58).

What P0304 means and what it costs

5P0301355386

The engine computer counted too many misfires in cylinder 1, meaning that one cylinder is failing to burn its fuel properly.

  • The make named most is Ford (144), then Honda (87) and Hyundai (28).
  • The Ford Escape (62) leads the models, ahead of the Ford Edge (42) and the Honda Odyssey (30).
  • Owners most often filed it beside P0304 (103), P0300 (103) and P0302 (51).

What P0301 means and what it costs

6P0420300393

The catalytic converter on bank 1, the side of the engine with cylinder 1, has stopped storing oxygen well enough, so the engine computer judges it is no longer cleaning the exhaust the way it should.

  • The make named most is Kia (100), then Chevrolet (41) and Hyundai (37).
  • The Kia Soul (89) leads the models, ahead of the Ford Focus (17) and the Hyundai Tucson (12).
  • Owners most often filed it beside P0430 (22), then P0300 (13) and P219A (11).

What P0420 means and what it costs

7P0700172297

The transmission control module found a fault of its own and asked the engine computer to turn on the check engine light. P0700 names no part: the fault itself is stored as a second code, which a basic reader may not show and a scan of the transmission module does.

  • The make named most is Chevrolet (99), then GMC (41) and Subaru (12).
  • The Chevrolet Silverado 1500 (30) leads the models, ahead of the GMC Sierra 1500 (16) and the Chevrolet Malibu (9).
  • Owners most often filed it beside P0747 (27), then P2714 (13) and P0776 (12).

What P0700 means and what it costs

8P0720165180

The computer lost, or stopped trusting, the signal from the transmission's output speed sensor, the part that reports how fast the transmission's output shaft turns.

  • The make named most is Ford (135), then Infiniti (23) and Nissan (5).
  • The Ford F-150 (124) leads the models, ahead of the Infiniti Q50 (19) and the Ford Mustang (6).
  • Owners most often filed it beside P0722 (42), then P0500 (17) and P0721 (9).

What P0720 means and what it costs

9P0299154160

Turbocharger underboost: the engine computer asked for more boost, the extra air pressure the turbo pushes into the engine, than it measured, and it may cut power.

  • The make named most is Chevrolet (48), then Ford (33) and Buick (19).
  • The Buick Encore (17) leads the models, ahead of the Chevrolet Cruze (11) and the Chevrolet Trax (11).
  • Owners most often filed it beside P0016 (5), P0365 (5) and P0369 (4).

What P0299 means and what it costs

10P0456148184

The evaporative emission (EVAP) system, which traps gasoline fumes from the fuel tank, has a very small leak, one as small as 0.020 inches (0.5 mm) across. It's the smallest of the three leak sizes the system tests for.

  • The make named most is Ford (78), then Jeep (12) and Chrysler (8).
  • The Ford Focus (32) leads the models, ahead of the Ford Escape (12) and the Ford Fusion (11).
  • Owners most often filed it beside P1450 (24), then P0420 (6) and P0455 (6).

What P0456 means and what it costs

11P0128121135

The engine didn't warm up enough: the coolant stayed below the temperature the engine computer needs before it will run its other self-tests. A thermostat stuck open is the usual reason.

  • The make named most is Chevrolet (44), then GMC (24) and Jeep (13).
  • The Chevrolet Blazer (41) leads the models, ahead of the GMC Acadia (24) and the Cadillac XT5 (9).
  • Owners most often filed it beside P01F0 (3), then P2181 (2) and U0401 (2).

What P0128 means and what it costs

12P0011109129

The engine computer found the intake camshaft's timing on bank 1, the side of the engine with cylinder 1, out of step with what it asked for. On most engines the part that moves that camshaft runs on engine oil.

  • The make named most is Chevrolet (38), then Hyundai (19) and GMC (12).
  • The Chevrolet Equinox (20) leads the models, ahead of the GMC Terrain (7) and the Hyundai Sonata (7).
  • Owners most often filed it beside P0014 (19), then P0010 (15) and P0016 (13).

What P0011 means and what it costs

13P0171104188

Bank 1 of the engine, the side with cylinder 1, is running lean. The engine computer added as much fuel as it is allowed to and the mixture still had too much air, so either air is getting in that the engine never measured, or fuel that should arrive isn't.

  • The make named most is Chevrolet (35), then Ford (12) and Toyota (11).
  • The Chevrolet Cruze (13) leads the models, ahead of the Chevrolet Sonic (8) and the Chevrolet Traverse (5).
  • Owners most often filed it beside P0174 (11), then P0131 (6) and P1101 (5).

What P0171 means and what it costs

14P043099137

The catalytic converter on bank 2 has stopped storing oxygen well enough, so the engine computer judges it is no longer cleaning the exhaust the way it should. Bank 2 is the side of a V6 or V8 without cylinder 1. Most four-cylinder engines have one bank and can't set this code.

  • The make named most is Honda (51), then Ford (24) and Jeep (4).
  • The Honda Pilot (43) leads the models, ahead of the Ford F-150 (17) and the Honda Odyssey (6).
  • Owners most often filed it beside P0420 (22), then P219B (12) and P219A (11).

What P0430 means and what it costs

15P017298102

Bank 1 of the engine, the side with cylinder 1, is running rich. The engine computer took away as much fuel as it is allowed to and the mixture still had too much fuel for the air coming in.

  • The make named most is Honda (71), then Kia (9) and Chevrolet (5).
  • The Honda CR-V (56) leads the models, ahead of the Honda Accord (7) and the Chevrolet Equinox (5).
  • Owners most often filed it beside P0303 (18), then P0301 (16) and P0304 (14).

What P0172 means and what it costs

16P01018391

The engine computer doesn't believe the airflow number sent by the mass air flow (MAF) sensor, the part that measures the air coming into the engine. The code doesn't prove the sensor itself is bad.

  • The make named most is Nissan (72), then Chevrolet (5) and Cadillac (1).
  • The Nissan Kicks (23) leads the models, ahead of the Nissan Sentra (20) and the Nissan Altima (11).
  • Owners most often filed it beside P0102 (5), then U0101 (2) and P1101 (2).

What P0101 means and what it costs

17P030578101

The engine computer counted too many misfires in cylinder 5, meaning that one cylinder is failing to burn its fuel properly.

  • The make named most is Chrysler (16), then Ford (10) and Jeep (9).
  • The Chrysler Pacifica (16) leads the models, ahead of the Ford F-150 (8) and the Jeep Wrangler (6).
  • Owners most often filed it beside P0300 (24), then P0304 (15) and P0301 (14).

What P0305 means and what it costs

18P030677101

The engine computer counted too many misfires in cylinder 6, meaning that one cylinder is failing to burn its fuel properly.

  • The make named most is Honda (14), then Ford (13) and Jeep (8).
  • The Ford F-150 (8) leads the models, ahead of the Honda Pilot (7) and the Jeep Wrangler (6).
  • Owners most often filed it beside P0300 (35), then P0304 (26) and P0302 (19).

What P0306 means and what it costs

19P04553787

The evaporative emission (EVAP) system, which traps gasoline fumes from the fuel tank, has a large leak, the biggest of the three sizes it tests for, such as a loose or missing gas cap.

  • The make named most is Ford (7), then Chevrolet (6) and Hyundai (4).
  • The Ford Fusion (5) leads the models, ahead of the Kia Soul (3) and the Mercury Milan (2).
  • Owners most often filed it beside P0456 (6), then P0457 (5) and P2119 (2).

What P0455 means and what it costs

20P04012849

Too little exhaust gas recirculation (EGR) flow: the engine computer saw less exhaust gas fed back into the engine than it expected. The code doesn't prove the EGR valve is bad.

  • The make named most is Chevrolet (11), then Volkswagen (3) and Hyundai (3).
  • The Chevrolet Volt (9) leads the models, ahead of the Volkswagen Jetta (3) and the Toyota Prius (2).
  • Owners filed it beside P1296 (1), P0106 (1) and P226C (1).

What P0401 means and what it costs

21P04412849

The engine computer checked the flow of fuel vapor from the charcoal canister into the engine and found it wrong in either direction: missing when the purge valve was open, or arriving when the valve was told to stay shut.

  • The make named most is Honda (5), then Jeep (4) and Toyota (4).
  • The models named most are the Jeep Wrangler (2), the Ford Focus (2) and the Honda CR-V (2).
  • Owners most often filed it beside P04F1 (4), then P0445 (3) and P0171 (3).

What P0441 means and what it costs

22P04422267

The evaporative emission (EVAP) system, which traps gasoline fumes from the fuel tank, has a small leak, at least as large as a hole 0.040 inches across. The code names a size, not a part.

  • The make named most is Chevrolet (11), then Land Rover (3) and Ford (2).
  • The models named most are the Chevrolet Impala (2), the Chevrolet Corvette (2) and the Ford Focus (2).
  • Owners most often filed it beside P0496 (3), then P0401 (1) and B1425 (1).

What P0442 means and what it costs

23P01741469

Bank 2 of the engine, the side without cylinder 1, is running lean. The engine computer added as much fuel as it is allowed to and the mixture still had too much air.

  • The make named most is Toyota (4), then Ford (2) and Ram (1).
  • The Toyota Highlander (3) leads the models, ahead of the Ram 1500 (1) and the Chevrolet Traverse (1).
  • Owners most often filed it beside P0171 (11), then P117B (2) and P0191 (2).

What P0174 means and what it costs

24P04431418

An electrical fault in the purge valve circuit. The engine computer sent a signal to the valve that lets trapped fuel vapor into the engine and didn't see the current it expected, which points at the valve's wiring or its coil, not at a leak.

  • The make named most is Ford (8), then Chevrolet (4) and Jeep (1).
  • The Ford Focus (5) leads the models, ahead of the Chevrolet Volt (4) and the Ford Escape (2).
  • Owners most often filed it beside P0031 (4), P0598 (4) and P0030 (4).

What P0443 means and what it costs

25P0440635

A general fault in the evaporative emission (EVAP) system, the sealed set of hoses, valves and a charcoal canister that traps gasoline fumes from the fuel tank. It's the older, broader code, reported mostly on cars built before 2010.

  • The make named most is Jeep (3), then Dodge (2) and Chrysler (1).
  • The models named most are the Dodge Durango (2), the Jeep Grand Cherokee (2) and the Jeep Renegade (1).
  • Owners filed it beside U1110 (1), U11BC (1) and U1120 (1).

What P0440 means and what it costs

26P0446435

The vent valve, which opens the fuel vapor system to outside air and seals it shut for the leak test, didn't do what the engine computer told it to. It's a valve that ignored an order, not a leak.

  • The makes named are Volkswagen (1), Mitsubishi (1) and Ford (1).
  • The models named are the Volkswagen Atlas (1), the Mitsubishi Outlander Sport (1) and the Ford Edge (1).
  • Owners filed it beside P0868 (1), P0776 (1) and P0172 (1).

What P0446 means and what it costs

Complaints from model years 2010 to 2025 Every model year since 1996

The numbers are in one JSON file, counted by the same tool behind the complaint figures on every code page.

Horizontal bar chart of the ten OBD-II codes named in the most NHTSA complaints for model years 2010 to 2025: P0302 449, P0300 394, P0303 383, P0304 358, P0301 355, P0420 300, P0700 172, P0720 165, P0299 154, P0456 148
The ten codes owners name most, of the codes on this page. Chart: Oil & Miles
Use this image

Free to republish under CC BY 4.0: credit Oil & Miles and link to this page. The snippet does both.


      

    


    
Check engine light codes by make

    
The codes owners of each make report most, among the codes on this page, for model years 2010 to 2025. A make appears once its owners have filed at least 30 complaints across these codes.

    

    
How to read your check engine light code

    
    
      
  1. Look at the light before you drive anywhere. A steady light means the car has stored a fault and wants it read. A flashing light is different: a flashing check engine light means a misfire bad enough to damage the catalytic converter, so slow down, avoid hard acceleration and get it checked right away.
    2. 
      
  2. Have the codes read, and read them all. Reading is free at most US parts chains, and a basic reader works on any car or light truck sold in the United States since the 1996 model year, because every one of them carries OBD-II. Ask for every code the scan finds, not the first one: codes often arrive together, and each code on this page lists what owners filed beside it.
    3. 
      
  3. Write the code down exactly, character by character. The first character is a letter and the rest are digits, so a code is P0301 rather than PO301 with a letter O. Some scan tools add a two-digit suffix, which is why the same fault appears as P0301 and as P030100. The suffix adds detail about the type of failure, and this page counts both under the base code P0301.
    4. 
      
  4. Do not clear it yet. Clearing wipes the freeze frame, the snapshot of what the engine was doing when the fault was recorded and the most useful thing a technician gets for free. It also resets the emissions monitors, and a car can fail an emissions inspection until the monitors finish running.
    5. 
      
  5. Look past a pointer code. Where a scan returns several codes, one of them is often a pointer rather than a fault: P0700 only says the transmission module has something to report, and the code stored beside it carries the detail.
    6. 
      
  6. Look the code up, then ask how the part is confirmed. Open your code above for the makes and models owners filed it on, and follow the link to its own page for what it costs, then ask the shop what test confirms the part before it is replaced. For a code that is not here yet, start with our list of check engine light codes.
    7. 
    


    
How this was counted

    
The source is NHTSA's consumer complaint database. NHTSA publishes owner complaints there, and this page uses it as of October 3, 2026.

    
One complaint counts once. The file writes a row for each component a complaint names, so rows are grouped on the complaint number before anything is counted.

    
A code counts in every form an owner writes it. P030100 with its fault byte, PO301 with a letter O, and a code run into the next word all count as P0301. A garbled number such as P03012 doesn't, and a range such as "P0301 through P0304" counts its two ends. A range written as a negative, such as "not between P0301 to P0304", doesn't count.

    
All model years means OBD-II cars. That column starts at the 1996 model year and leaves out rows that aren't a car: a trailer, a test record, a blank make.


    
What this data cannot tell you

    
It is not a failure rate. A code shows up here only when an owner typed it into a complaint, and most owners never file one. A code that feels like nothing from the driver's seat can be common on the road and rare in this table.

    
It is not a verdict on a make. A make with more cars on the road draws more complaints, so the makes column says where reports pile up, not which cars are worse.


    

      
Common questions

      
What is the most common check engine light code?
 
Among the codes on this page, P0302, with 449 complaints for model years 2010 to 2025, then P0300 with 394. Across the federal file, for model years 2010 to 2025, the code named most is P1326, in 460 complaints, and P2111, C1391 and C0020 are also near the top; they will be added as their pages are written.

      
What does OBD-II mean?
 
On-board diagnostics, second generation, also written OBD2 or OBD II. It's the self-testing system every car and light truck sold in the United States since the 1996 model year has to carry, and it stores what it finds as diagnostic trouble codes, or DTCs, the five-character codes this page counts.

      
Does this show how often a code happens on the road?
 
No. It counts complaints owners filed with NHTSA that name the code, and most owners never file one. A code that causes nothing a driver notices can be common on the road and rare here.

      
What do the letters P, B, C and U at the start of a code mean?
 
The first character names the system that set the code. P is powertrain, the engine and transmission, and every code on this page is a P code today. The other three turn up in the complaint record too: a B code arrives with body electronics, as B1425 does beside an inflatable restraint module; a C code with the chassis, as C0020 does beside an ABS hydraulic unit; and a U code where modules have stopped talking to each other. The code's shape is set by SAE J2012, the standard California's OBD II regulation requires manufacturers to use. We haven't read J2012 itself, so those three are what the record shows rather than the standard's own wording. Codes from those systems will join this page as their pages are written.

    


    
How to cite this

    
Free to quote and republish under CC BY 4.0: credit Oil & Miles and link here. The chart above carries the same licence, and the numbers behind it are in the data file.

    

      
Cite Oil & Miles (2026). Most common check engine light codes reported (OBD-II), model years 2010-2025. https://oilandmiles.com/reports/obd-ii-most-common-check-engine-light-codes 

      
APA Oil & Miles. (2026). Most common check engine light codes reported (OBD-II), model years 2010-2025 [Data report]. https://oilandmiles.com/reports/obd-ii-most-common-check-engine-light-codes 

    

    
For journalists. Questions about the method are answered the same day through the contact page. Our other data pages are the most complained-about cars report and the complaint statistics page.


    

      
Sources

      
    
        
  1. California Code of Regulations, Title 13, section 1968.2, the OBD II
            regulation, read at source: it lists SAE J2012, "Diagnostic Trouble Code Definitions"
            and requires that "standardized fault codes conforming to SAE J2012 shall be employed".
            The regulation, read September 23, 2026.
    2. 
        
  2. NHTSA's consumer complaint database. nhtsa.gov/nhtsa-datasets-and-apis, as of October 3, 2026, the same data behind every code page.
    3. 
      

    


    
26 codes, model years 2010 to 2025 unless a column says otherwise, read October 14, 2026. This page is general information about what owners reported, not advice about a specific car. Rebuilt each quarter.