Check Engine light on Chrysler: why it comes on, error code decoding, and how to fix it

ByAlex Smidt

The Check Engine light on your Chrysler is a serious alert you should never overlook. It indicates that the engine control unit has detected a fault in the engine, emissions, or related systems. Whether you drive a Chrysler 300, Pacifica, Voyager, Town & Country, or 200, this warning can appear suddenly after refueling, during acceleration, or even on a cold start. Ignoring it may lead to increased fuel consumption, loss of power, or expensive component damage. This guide explains the most common causes, decodes 20 frequent error codes, and provides clear solutions to help you resolve the issue quickly and keep your Chrysler running reliably.

Why the Check Engine light activates on Chrysler vehicles

The indicator comes on when the powertrain control module registers deviations from normal parameters in fuel delivery, ignition, exhaust, or sensor operation. On Chrysler models the light may stay solid or flash during misfires. Many triggers are simple and inexpensive to fix, such as a loose gas cap or dirty sensors, while others involve more complex components like the catalytic converter or transmission. Prompt diagnosis prevents minor issues from turning into major repairs. The essential first step is always scanning for diagnostic trouble codes using an OBD-II tool.

Main reasons the light comes on

  • Worn or fouled spark plugs and ignition coils
  • Faulty oxygen sensors (lambda sensors)
  • Air leaks or dirty mass airflow sensor
  • Problems in the EVAP fuel vapor recovery system
  • Low efficiency of the catalytic converter
  • Issues with fuel injectors or fuel pump
  • Malfunctioning crankshaft or camshaft position sensors
  • Engine overheating or poor fuel quality

Decoding common error codes and fixes

P0101 — Mass airflow sensor circuit range or performance problem. Cause: contamination or failure. Fix: clean with appropriate cleaner or replace the sensor.

P0102 / P0103 — Low or high input from mass airflow sensor. Cause: damaged wiring or short. Fix: repair wiring or replace sensor.

P0117 / P0118 — Engine coolant temperature sensor circuit low or high. Cause: faulty sensor. Fix: replace sensor and check coolant.

P0122 / P0123 — Throttle position sensor circuit low or high. Cause: wear or dirt buildup. Fix: clean throttle body and replace sensor.

P0131 / P0132 — Oxygen sensor circuit low or high voltage (bank 1 sensor 1). Cause: contamination or failure. Fix: replace the oxygen sensor.

P0171 — System too lean (bank 1). Cause: vacuum leak, dirty MAF, or weak fuel pump. Fix: seal leaks, clean sensor, check fuel pressure.

P0172 — System too rich (bank 1). Cause: clogged injectors or faulty regulator. Fix: clean or replace injectors.

P0300 — Random or multiple cylinder misfire detected. Cause: spark plugs, coils, or injectors. Fix: replace plugs and test coils.

P0301–P0304 — Misfire in cylinder 1 to 4. Cause: bad spark plug or coil on that cylinder. Fix: diagnose and replace per cylinder.

P0327 — Knock sensor circuit low input. Cause: damaged knock sensor. Fix: replace the sensor.

P0335 — Crankshaft position sensor circuit malfunction. Cause: wiring or sensor failure. Fix: inspect and replace sensor.

P0340 — Camshaft position sensor circuit malfunction. Cause: wear or wiring issue. Fix: replace the camshaft sensor.

P0401 — Exhaust gas recirculation flow insufficient. Cause: clogged EGR valve. Fix: clean or replace EGR valve.

P0420 — Catalyst system efficiency below threshold (bank 1). Cause: worn catalytic converter. Fix: replace the converter (follow local regulations).

P0442 — Evaporative emission system leak detected (small leak). Cause: loose gas cap. Fix: tighten or replace the cap.

P0455 — Evaporative emission system leak detected (large leak). Cause: damaged hoses or purge valve. Fix: inspect and repair EVAP system.

P0507 — Idle air control system RPM higher than expected. Cause: dirty throttle body. Fix: thorough throttle body cleaning.

P0601 — Internal control module memory checksum error. Cause: ECU issue. Fix: reflash software or replace module.

P0700 — Transmission control system malfunction. Cause: automatic transmission problem. Fix: perform transmission diagnostics.

P2135 — Throttle/pedal position sensor switch A/B voltage correlation. Cause: worn accelerator pedal sensors. Fix: replace pedal assembly.

Useful tips for diagnosis and prevention

Begin every diagnosis by reading codes with a quality OBD-II scanner. After repairs, clear the codes but complete several drive cycles so the system can confirm the fix. Replace spark plugs according to the maintenance schedule (typically every 30-60 thousand km), use high-quality fuel, and service air and fuel filters regularly. These habits greatly reduce the chance of the Check Engine light appearing on your Chrysler. If the light flashes, stop driving immediately to protect the catalytic converter and engine. Professional diagnostics at a trusted workshop help identify hidden faults early and ensure long-term reliability.