Chevrolet OBD Codes: Meaning & Fixes

P0420 Powertrain The bank 1 catalytic converter no longer stores enough oxygen to clean the exhaust properly. Low C0035 Chassis The ABS module lost a valid signal from the driver-side front wheel speed sensor. Moderate P0171 Powertrain The engine computer is adding the maximum extra fuel it's allowed on bank 1 and still sees… Moderate P0299 Powertrain The turbo or supercharger isn't building the boost pressure the engine computer is asking for. Moderate P0300 Powertrain The engine computer sees misfires that jump between cylinders or hit several cylinders at once. High P0304 Powertrain Cylinder 4 is misfiring. Its end or rear position makes water, oil and intake leaks common… Moderate

P1404 Chevrolet · Powertrain The electric EGR valve on a Chevy isn't fully closing when the PCM commands it shut. Low P1441 Chevrolet · Powertrain Engine vacuum is reaching the fuel tank even though the PCM has the EVAP purge valve turned off. Low P1516 Chevrolet · Powertrain The electronic throttle didn't move to where the computer commanded, so the engine drops into… Moderate P1626 Chevrolet · Powertrain The engine computer lost the 'OK to fuel' signal from the Chevy anti-theft system, so it may… Moderate P1631 Chevrolet · Powertrain The engine computer received the wrong anti-theft password, so it blocks starting or fuel. Moderate P1682 Chevrolet · Powertrain The engine computer's two ignition power feeds disagree, which can cause stalling or Reduced… High P1E00 Chevrolet · Powertrain Volt/Bolt pointer code: the hybrid/EV controller found a fault and asked for the check engine… Moderate P20EE Powertrain The SCR catalyst isn't removing enough NOx; DEF quality, dosing, a NOx sensor or the catalyst… Moderate P2108 Powertrain The throttle control module isn't performing as expected – check its power, data link… Moderate P2135 Powertrain The two position signals inside the throttle body disagree, so the PCM can no longer trust… Moderate P2138 Powertrain The two sensors in the gas pedal report different pedal positions, so the PCM limits throttle… Moderate P2198 Powertrain Bank 2's front sensor keeps claiming rich, so the PCM leans out that side of the engine more… Low P25A2 Chevrolet · Powertrain The brake module stored a fault and asked the engine computer to turn on the check engine light. Moderate P3400 Powertrain Cylinder shut-off on bank 1 (AFM, DFM, MDS or VCM) isn't doing what the engine computer… Moderate P3401 Powertrain The engine computer sees a broken or open circuit to the solenoid that shuts off cylinder 1. Low U0101 Network The engine computer and other modules stopped hearing from the transmission control module. 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 U0401 Network The engine computer is still on the network, but another module doesn't trust the numbers it's… Moderate U1000 Chevrolet · Network A module on an older GM's Class 2 data line couldn't communicate, so modules stopped hearing… Moderate U1064 Chevrolet · Network Other modules stopped hearing the body control module on an older GM's Class 2 data line. Moderate U1096 Chevrolet · Network Other modules on an older GM's Class 2 network stopped receiving messages from the gauge… Low