Limp mode: Codes, Causes & Fixes

Limp mode (also called reduced power or fail-safe mode) is the vehicle protecting itself: the engine or transmission computer limits power, RPM or gear selection after detecting a fault. Typical triggers are throttle pedal or throttle body faults, turbo boost problems and transmission sensor or solenoid faults. Drive gently to a safe place or a shop; restarting may clear it temporarily, but the stored codes show the real cause.

165Codes

3.3Average severity

28%High or critical

4%DIY-friendly

Severity distribution

Most viewed

P0299 Powertrain The turbo or supercharger isn't building the boost pressure the engine computer is asking for. Moderate P0606 Powertrain The engine computer failed its own internal self-test – check its power and grounds before… Moderate P0700 Powertrain The transmission computer found a fault and asked for the check engine light – read the TCM… Moderate P2002 Powertrain The ECU thinks the diesel particulate filter isn't trapping soot properly — or it can't measure… Moderate 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

All codes (46)

All Severity 3+ Severity 4+

P2100 Powertrain The computer can't push current through the throttle motor – the circuit to the throttle body… High P2104 Powertrain A fail-safe has locked the engine at idle and the gas pedal no longer works – another code… High P2107 Powertrain The processor supervising the electronic throttle failed its self-check – a computer fault, not… High P2111 Powertrain The throttle plate stayed more open than commanded – a real safety concern until you know why. High P2112 Powertrain The PCM asked the throttle to open, but it stayed shut – the engine can't get air, so it bogs… High P2146 Powertrain The shared power feed for one group of injectors is open, so every injector in that group has… High P2463 Powertrain The DPF is loaded with more soot than the ECU allows; it needs a regen or cleaning before it… High P246C Powertrain The DPF is so restricted that the ECM has cut engine power to protect the turbo, EGR system… High 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 U0107 Network The engine computer can't reach the module that drives the electronic throttle, so power is cut… 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

Symptoms

Check engine light on 558 Loss of power 214 Rough idle 184 Poor fuel economy 146 Engine stalling 133 Car won't start 123 Harsh or slipping shifts 80 ABS / traction light on 65 Fuel smell 34 Check engine light flashing 22