Vehicle fluid capacities and specs
What your check engine light is telling you
Oil, coolant and fluid capacities for the exact year, make and model.
Most common trouble codes
What the code means, whether it is safe to drive, and what usually fixes it.
- P0420Catalyst efficiency below threshold, bank 1
- P0300Random or multiple cylinder misfire
- P0171System too lean, bank 1
- P0174System too lean, bank 2
- P0442EVAP system small leak
- P0455EVAP system large leak
- P0456EVAP system very small leak
- P0440EVAP system malfunction
- P0128Coolant below thermostat temperature
- P0401EGR flow insufficient
- P0301Cylinder 1 misfire
- P0011Camshaft timing over-advanced, bank 1
- P0135O2 sensor heater circuit, bank 1 sensor 1
- P0700Transmission control system fault
- U0100Lost communication with ECM/PCM
Sections
- Diagnostic Trouble CodesEvery code on this site is the SAE J2012 generic definition — the wording the standard itself uses, not a paraphrase. Where a code is defined by the manufacturer rather than by SAE, the page says so, because a definition found for the wrong marque is worse than no definition at all.12,186 pages →
- Fuel Economy by ModelEvery figure here comes from the EPA's own test database — the same numbers printed on the window sticker of a new car. They are laboratory results produced on a standardised cycle so that any two cars can be compared on identical terms, not a prediction of what you will see.26,359 pages →
Latest
- P0509 Code: Idle Air Control Circuit High, and Why It Mostly Shows Up on Older EnginesP0509 is an idle control code from the era before electronic throttles. On most vehicles that set it, the fault is a dirty bore, a connector or the valve itself, in that order of likelihood.Diagnostic Trouble Codes · 8 min read
- P057C Code: Brake Pedal Position Sensor Circuit Low, and the GM Truck Problem Behind Most of ThemP057C is a brake pedal sensor code, and on full-size GM trucks it often comes with odd driving symptoms: braking on flat roads, power that will not come, a transmission that keeps shifting. GM bulletins trace most of it to wiring and a learned voltage.Diagnostic Trouble Codes · 6 min read
- U0181 Code: Lost Communication With the Headlamp Leveling ModuleU0181 is a network code: the headlamp leveling module has gone quiet on the data bus. The headlights still work, but they stop adjusting to load, and on some cars the main beam or adaptive lighting shuts off too.Diagnostic Trouble Codes · 6 min read
- U0405 Code: Invalid Data From the Cruise Control Module, and What the -64, -68 and -86 Endings MeanOn a modern car, the cruise control module in U0405 is usually the radar behind the grille. The code says its data failed a check, and the two digits after the dash say which check.Diagnostic Trouble Codes · 6 min read
- U0421 Code: Invalid Data From the Suspension Control Module, on Land Rover and GM VehiclesU0421 is a data-validity code for the ride height and air suspension system. On some vehicles it is a real fault, on others a known false report with a published fix.Diagnostic Trouble Codes · 6 min read
- P0802 Code: Transmission MIL Request Circuit, and Why It Often Points to the Batteries on Diesel TrucksP0802 is a code about a message, not a gearbox. The transmission computer could not ask the engine computer to light the check engine lamp, and the reason is usually power, ground or wiring between the two.Diagnostic Trouble Codes · 6 min read
- P053E Code: Crankcase Pressure Too High, and What to Check Before You Blame the EngineHigh crankcase pressure has two possible sources: more gas getting into the crankcase, or less getting out. P053E cannot tell which, but a few simple checks can.Diagnostic Trouble Codes · 6 min read
- P0912 Code: Gate Select Actuator Circuit Low on Automated Manual GearboxesP0912 belongs to automated manual gearboxes: ordinary manual gearboxes with a computer and actuators doing the clutch and the shifting. The gate select actuator moves the lever sideways between gear planes, and a low circuit usually means a wiring or connector fault.Diagnostic Trouble Codes · 6 min read
- P0943 Code: Hydraulic Pressure Unit Cycling Too Often, and What a Short Pump Cycle MeansAn electro-hydraulic gearbox keeps a store of pressure in an accumulator and only runs its pump to top it up. P0943 says the pump is topping up too often, which means pressure is leaving the system faster than normal.Diagnostic Trouble Codes · 6 min read
- P08A6 Code: Gear Lever Position Sensors Disagree, on Shift-by-Wire SelectorsAn electronic gear selector reports its position through several sensors at once so that one bad reading cannot put the car in the wrong gear. P08A6 means those sensors stopped agreeing.Diagnostic Trouble Codes · 6 min read
- B0048 Code: Third Row Right Side Airbag Deployment Circuit, and What the Suffix SaysB0048 is an airbag code for the third row of a three-row vehicle. The airbag in question is disabled until the fault is fixed, and the two digits after the dash usually tell you whether you are looking for a short, an open or a resistance problem.Diagnostic Trouble Codes · 6 min read
- P0171 Code: System Too Lean, Bank 1, Reading the Fuel Trims That Set It, and the Ford and Kia Cases Where the Leak Was Not a LeakP0171 is a number that ran out of room. The computer kept lengthening injector pulses on bank 1 and the exhaust still said lean. Where the trims are high tells you why: at idle it is unmetered air, under load it is fuel supply, everywhere it is the sensor that measures air. The bulletins add two cases with no leak at all.Diagnostic Trouble Codes · 8 min read