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
P0174
Powertrain
The cylinder bank without cylinder 1 is running lean even with the maximum fuel correction…
Moderate
P0420
Powertrain
The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly.
Low
B0001
Body
The airbag module found a fault in the firing circuit for the driver's front airbag (stage 1).
High
C0035
Chassis
The ABS module lost a valid signal from the driver-side front wheel speed sensor.
Moderate
P0101
Powertrain
The MAF sensor's airflow reading doesn't match what the engine computer expects…
Low
P0113
Powertrain
The intake air temperature signal is stuck at maximum voltage, which usually means an open…
Low
All codes (648)
P090C
Ford · Powertrain
The PowerShift TCM sees a low signal on the motor that works clutch B, the even-gear…
Moderate
P0A0F
Powertrain
The hybrid system spun the gas engine with its motor-generator to start it, but the engine…
High
P0A1F
Powertrain
The module that manages the high-voltage battery failed its self-check or reports implausible…
Moderate
P0A7E
Powertrain
The high-voltage battery got too hot. A clogged cooling intake or dirty fan is the usual cause.
Moderate
P0A7F
Powertrain
The battery computer has calculated that the whole high-voltage pack has worn past its usable…
Moderate
P0A80
Powertrain
The hybrid system sees weak or unbalanced modules in the high-voltage battery and flags…
Moderate
P0A93
Powertrain
The inverter's separate coolant loop isn't carrying heat away – usually a dead electric…
High
P0A94
Powertrain
A hybrid voltage converter isn't delivering the voltage it should – on Toyotas, the boost…
High
P0A95
Powertrain
The main fuse in the high-voltage battery circuit has opened or its circuit reads open…
Critical
P0AA6
Powertrain
High voltage is leaking toward the car body somewhere – an insulation fault that must be found…
High
P0AFA
Powertrain
Total high-voltage battery voltage dropped below the minimum the system allows, so power…
High
P1000
Ford · Powertrain
Ford's computer hasn't finished all its self-tests yet. It's a status message, not a fault.
Minor
P1101
Chevrolet · Powertrain
GM's engine computer found that measured airflow doesn't agree with what it expects.
Low
P1128
Jeep · Powertrain
Your Jeep's PCM never switched bank 1 from preset fueling to O2-sensor feedback after…
Low
P1128
Volkswagen · Powertrain
VW's part-load fuel adaptation has maxed out adding fuel on bank 1 – the engine runs lean as…
Moderate
P1129
Jeep · Powertrain
The PCM couldn't switch bank 2 of your Jeep's V6 or V8 into oxygen-sensor-controlled fueling…
Low
P1131
Ford · Powertrain
Ford's front O2 sensor on bank 1 stays lean even after the PCM has added all the fuel it…
Low
P1132
Ford · Powertrain
Ford's front O2 sensor on bank 1 keeps reading rich even though the PCM has pulled out as much…
Low
P1133
Chevrolet · Powertrain
The front oxygen sensor on bank 1 isn't flipping between rich and lean often enough during GM's…
Low
P1134
Chevrolet · Powertrain
Bank 1's front O2 sensor reacts much faster in one direction (rich or lean) than the other.
Low
P1135
Toyota · Powertrain
The heater inside Toyota's upstream air/fuel ratio sensor is drawing too much or too little…
Low
P1136
Volkswagen · Powertrain
At idle the VW computer is adding the maximum fixed amount of fuel on bank 1 – a classic vacuum…
Low
P1137
Volkswagen · Powertrain
At idle the VW computer is pulling out as much fuel as it's allowed on bank 1 and the mix…
Low
P1151
Ford · Powertrain
On a Ford V6 or V8, the front O2 sensor on the bank 2 side stays lean and never switches back…
Low
P1152
Ford · Powertrain
On a Ford V6 or V8, the bank 2 front O2 sensor sticks on rich even after the PCM leaned that…
Low
P1153
Chevrolet · Powertrain
The front O2 sensor on the passenger-side bank of a Chevy V6/V8 isn't cycling rich-lean often…
Low
P1154
Chevrolet · Powertrain
On a Chevy V6/V8, the bank 2 front O2 sensor rises and falls at clearly different speeds.
Low
P1155
Toyota · Powertrain
The heater in the front-bank air/fuel ratio sensor of a Toyota V6 or V8 is out of its current…
Low
P1157
Honda · Powertrain
The signal lines of Honda's upstream air/fuel ratio sensor read too high, usually an open…
Low
P1166
Honda · Powertrain
The circuit that powers the heater in Honda's upstream A/F sensor is open, shorted or unpowered.
Low