CarFaultIQ

OBD-II Code Decoder

Search the licensed P, B, C, and U reference library by code, definition, system, or manufacturer. Reference-only results are not a complete diagnosis.

  • 12,128 OBD-II codes
  • 18,805 reference definitions
  • 16,185 publicly searchable across 10,181 codes

Review-withheld definitions are excluded; lookup records are not published diagnostic pages.

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P0304 — vehicles with official records naming this code

P0304 is named in NHTSA-published manufacturer communications or investigations for 59 vehicle families, including:

  • Chevrolet Tahoe model years 2007-2008, 2010-2013, 2021 · 10 records
  • Ford GT model years 2017-2022 · 10 records
  • GMC Yukon model years 2007-2008, 2010-2013, 2021 · 10 records
  • Kia Forte model years 2010, 2017-2019 · 10 records
  • Cadillac Escalade model years 2007-2008, 2010-2013, 2021 · 9 records
  • Chevrolet Suburban model years 2007-2008, 2010-2013, 2021 · 9 records
  • Cadillac CTS model years 2004-2005, 2008-2013 · 8 records
  • Audi A6 model years 2019-2021 · 7 records
  • Audi A7 model years 2019-2021 · 7 records
  • Audi Q8 model years 2019-2021 · 6 records

A code named in a manufacturer communication means the document refers to it for those vehicles. It is not a diagnosis of any car, and it does not mean the code is common on that vehicle.

Matching definitions: 2 · Unique codes: 1.

Code Meaning System Scope Manufacturer Severity
P0304 Cylinder 4 Misfire Detected Engine & drivability Generic Not manufacturer-specific Not classified
P0304 Worn out spark plugs, ignition wires, coil(s), distributor cap and rotor (when applicable), Incorrect ignition timing, Vacuum leak(s), Low or weak fuel pressure, Improperly functioning EGR system, Defective Mass Air Flow Sensor, Defective Crankshaft and or Camshaft Sensor, Defective Throttle Position Sensor, Mechanical engine problems (i.e.—low compression, leaking head gasket(s), or valve problems) Powertrain Manufacturer-specific Audi Not classified