Trouble codes

Trouble codes, one page each

What the code means, the usual causes in checking order and what to test before you buy a part. To decode any code, use the code decoder.

P0011: Cam timing over-advancedP0011 means bank 1 intake cam timing is more advanced than commanded. Learn the causes, from low oil to a sticking oil control valve, and how to fix it.Engine and emissions codes (P0)
P0014: Exhaust cam timing over-advancedP0014 means the bank 1 exhaust camshaft is more advanced than the computer commanded. Learn the causes, from low oil to a stuck VVT solenoid, and how to fix it.Engine and emissions codes (P0)
P0016: Crank and cam timing correlation codeP0016 means the crank and cam position signals do not line up on bank 1. Learn the causes, from low oil to timing chain wear, and how to diagnose it.Engine and emissions codes (P0)
P0101: MAF reading out of rangeP0101 means the MAF sensor reading does not match what the computer expects. See the symptoms, common causes like a dirty MAF or air leak, tests and fixes.Engine and emissions codes (P0)
P0118: Coolant temp sensor reads too coldP0118 means the coolant temperature sensor signal is too high, so the PCM sees a very cold engine. Learn the causes, how to test it, and how to fix it.Engine and emissions codes (P0)
P0128: Engine not warming up codeP0128 means the engine takes too long to warm up, usually from a thermostat stuck open. Learn the symptoms, causes, how to test it, and how urgent it is.Engine and emissions codes (P0)
P0135: O2 sensor heater faultP0135 means a fault in the upstream O2 sensor heater circuit on bank 1. Learn the causes, how to test the fuse, heater and wiring, and how to fix it.Engine and emissions codes (P0)
P0141: Downstream O2 heater faultP0141 means the heater in the downstream O2 sensor on bank 1 has a circuit problem. What it means, common causes, how to test it, and how to fix it.Engine and emissions codes (P0)
P0171: Engine running leanP0171 means bank 1 is running lean. Learn what causes it, how to read fuel trims to find the problem, how to fix it, and whether it is safe to drive.Engine and emissions codes (P0)
P0172: Engine running rich (bank 1)P0172 means bank 1 is running rich and the computer cannot pull enough fuel. Learn the symptoms, common causes, how to read fuel trims, and how to fix it.Engine and emissions codes (P0)
P0174: Lean condition, bank 2P0174 means bank 2 is running lean and fuel trims have maxed out. Common causes, how to read fuel trims to find the problem, and how to fix it.Engine and emissions codes (P0)
P0299: Low boost / underboostP0299 means the turbo or supercharger is making less boost than the engine computer expects. Causes, how to diagnose boost leaks, fixes, and driving advice.Engine and emissions codes (P0)
P0300: Random misfire codeP0300 means the engine is misfiring in more than one cylinder or at random. See the causes, how to diagnose it, and why a flashing light means stop driving.Engine and emissions codes (P0)
P0301: Single cylinder misfireP0301 to P0306 mean a misfire in one specific cylinder. Learn how to read the cylinder number, run a swap test, find the cause and fix it safely.Engine and emissions codes (P0)
P0325: Knock sensor circuit faultP0325 means a problem in the knock sensor 1 circuit. Learn the symptoms, common causes, how to test the sensor and wiring, and whether you can keep driving.Engine and emissions codes (P0)
P0335: Crank sensor circuit codeP0335 means the engine computer has a problem with the crankshaft position sensor signal. Learn the symptoms, causes, how to test it, and if you can drive.Engine and emissions codes (P0)
P0340: Camshaft sensor signal faultP0340 means the computer is not getting a valid signal from camshaft position sensor A on bank 1. See the symptoms, causes, tests and whether you can drive.Engine and emissions codes (P0)
P0401: Low EGR flowP0401 means the engine computer saw too little exhaust gas recirculation flow. Common causes like carbon-clogged passages, how to diagnose it, and how to fix it.Engine and emissions codes (P0)
P0420: Catalyst efficiency codeP0420 means the bank 1 catalytic converter is not cleaning exhaust as well as it should. Causes, how to diagnose it, how to fix it, and whether you can drive.Engine and emissions codes (P0)
P0430: Catalyst efficiency code, bank 2P0420 and P0430 mean the same thing on different sides of the engine. How to find bank 1 and bank 2, what causes each code, and what to check first.Engine and emissions codes (P0)
P0442: Small EVAP leakP0442 means the EVAP system found a small leak. Learn the common causes, how to find the leak, what a scan tool shows, and whether it is safe to drive.Engine and emissions codes (P0)
P0446: EVAP vent valve codeP0446 points to the EVAP canister vent valve or its circuit. Learn what it means, the common causes, how to diagnose it with a scan tool, and how to fix it.Engine and emissions codes (P0)
P0449: EVAP vent valve circuit faultP0449 means the computer sees an electrical fault in the EVAP vent valve circuit. See the symptoms, common causes, how to test it, and how to fix it.Engine and emissions codes (P0)
P0455: Large EVAP leak codeP0455 means the EVAP system found a large leak. Learn the common causes, starting with the gas cap, how to diagnose it, and how urgent it is.Engine and emissions codes (P0)
P0456: EVAP very small leakP0456 means the EVAP system found a very small vapor leak. Learn the common causes, how to find the leak, and whether it is safe to keep driving.Engine and emissions codes (P0)
P0496: EVAP purge flow codeP0496 means fuel vapor is flowing to the engine when the purge valve should be closed. Learn the causes, how to test the purge valve, and how to fix it.Engine and emissions codes (P0)
P0606: Engine computer fault codeP0606 means the engine computer found an internal processor fault. Learn the common causes, from low voltage to software, how to diagnose it, and next steps.Engine and emissions codes (P0)
P0705: Transmission range sensor faultP0705 means the computer got an invalid signal from the transmission range sensor. See the symptoms, causes, how to test it and the safety risks of driving.Engine and emissions codes (P0)
P2263: Turbo boost performance problemP2263 means actual boost does not match what the engine computer expects. Learn the common causes, how to test for boost leaks, and how to fix it.Engine and emissions codes (P0)
U0001: CAN bus communication codeU0001 means a fault on the high speed CAN network that lets modules talk. Learn the symptoms, common wiring and module causes, and how to diagnose it safely.ABS, airbag and network codes (C, B, U)
U0100: No communication with engine computerU0100 means a module lost contact with the engine computer on the vehicle network. Causes, from a weak battery to CAN wiring faults, and how to diagnose it.ABS, airbag and network codes (C, B, U)
U0101: No communication with transmission moduleU0101 means a module stopped hearing from the transmission control module. Learn the common causes, how to diagnose the network, and if it is safe to drive.ABS, airbag and network codes (C, B, U)
OBD2 scanner says no link or won't connect: what to checkOBD2 scanner says no link or won't connect? Check ignition, the port fuse, pins, battery voltage, protocol support and Bluetooth pairing in this order.Choosing a scan tool
Check engine light on but the car runs fineCheck engine light on but the car runs fine? Here are the usual causes, how to read the code, and when it is still worth fixing soon even with no symptoms.Engine and emissions codes (P0)
Check engine light after refuelingCheck engine light after getting gas? A loose or worn gas cap often sets an EVAP leak code. How to confirm it, what codes to expect, and when it is something else.Engine and emissions codes (P0)
Airbag or SRS warning light onAirbag light on? The SRS system has found a fault and the airbags may not deploy. Common causes, how to read SRS codes safely, and why repairs belong with a pro.ABS, airbag and network codes (C, B, U)
ABS light on: common causes and how to read the codeABS light on? The common causes, from wheel speed sensors to low brake fluid, whether it is safe to drive, and how to read ABS codes with the right scanner.ABS, airbag and network codes (C, B, U)