OBD-II Trouble Codes: Meaning & Fixes
OBD-II trouble codes are five-character codes stored by your vehicle's computers when a monitored system goes out of range. Browse them by system (P, B, C, U), by sub-system or by the symptom you notice. Each code page explains what the code means, how serious it is, whether you can keep driving, the likely causes in order, how to diagnose it and what repairs typically cost.
648Codes
2.8Average severity
16%High or critical
18%DIY-friendly
Severity distribution
Most viewed
P0302
Powertrain
Cylinder 2 keeps misfiring. On inline engines it's a middle cylinder, so rule out coolant…
Moderate
P0174
Powertrain
The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction…
Moderate
P0011
Powertrain
The bank 1 intake cam sits further advanced than the PCM asked for, usually an oil or control…
Moderate
P0218
Powertrain
The transmission fluid got hotter than the computer allows, from heavy load, low fluid…
High
P0301
Powertrain
Cylinder 1 is repeatedly failing to fire. The cause is almost always its coil, plug, injector…
Moderate
P0014
Powertrain
The bank 1 exhaust cam won't follow its target and stays too far advanced; think oil, valve…
Moderate
All codes (104)
U0001
Network
A module found the high-speed CAN network itself misbehaving, not just one silent module.
High
U0073
Network
A module saw so many errors on CAN bus A that it shut off its own transmitter.
High
U0100
Network
Another module stopped hearing from the engine computer on the CAN network.
High
U0101
Network
The engine computer and other modules stopped hearing from the transmission control module.
High
U0103
Network
The electronic shifter (dial, knob or joystick) stopped talking to the transmission and engine…
High
U0105
Network
The PCM lost contact with the separate module that fires the injectors, common on diesel…
High
U0107
Network
The engine computer can't reach the module that drives the electronic throttle, so power is cut…
High
U0109
Network
The PCM lost contact with the module that controls fuel pump speed; stalling or no-start can…
High
U0110
Network
The hybrid/EV system lost contact with the module that runs electric drive motor A.
Critical
U0115
Network
Modules lost contact with the second engine computer on vehicles that use two of them.
High
U0131
Network
The electric power steering module dropped off the network; steering assist may be reduced…
High
U0151
Network
Other modules can't reach the airbag computer, so the airbags and seatbelt pretensioners may…
High
U0404
Network
The electronic shifter reports a lever position the transmission can't trust, so Park may not…
High
U0418
Network
Brake-control data such as pedal position or brake-assist status looks implausible to another…
High