LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Chrysler >> 2001 >> PT Cruiser Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0401: EGR System Failure >> Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0401: EGR System Failure: Testing

NOTE: Before proceeding, inspect all vacuum hoses related to EGR system.
  1. Start engine and warm to normal operating temperature. Let engine idle. If engine idles smoothly, go to next step. If engine does not idle smoothly, go to step  9 .
  2. Turn ignition on. Turn all accessories off. Ensure engine is at normal operating temperature. Using scan tool, select ENGINE SYSTEM TEST, then EGR SYSTEM TEST. Actuate FLOW function. If engine runs rough or stalls, go to next step. If engine does not run rough or stall, go to step  4 .
  3. Turn ignition off. Visually inspect related wiring harness. Check for chafed, pierced, pinched or partially broken wires. Visually inspect related wiring harness connectors. Check for broken, bent, pushed out or corroded terminals. Refer to any Technical Service Bulletins (TSBs) that may apply. If a problem is found, repair as necessary. If no problems are found, test is complete.
  4. Turn ignition off. Ensure all accessories are turned off. Disconnect EGR solenoid harness connector. See Figure . Connect a test light between EGR solenoid harness connector terminals. Turn ignition on. Using scan tool, actuate EGR solenoid. If test light does not flash, go to next step. If test light flashes, replace EGR valve.
  5. Turn ignition off then on. Using scan tool, actuate ASD relay. Connect a test light between ground and ASD relay output circuit (Dark Green/Orange wire) at EGR solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, repair open in ASD relay output circuit.
  6. Turn ignition off then on. Measure voltage between ground and control circuit (Gray/Yellow wire) at EGR solenoid harness connector. If voltage is 4.9 volts or less, go to next step. If voltage is more than 4.9 volts, repair short to voltage in Gray/Yellow wire between EGR solenoid and PCM.
  7. Turn ignition off. Disconnect PCM harness connectors. See Figure . Measure resistance of control circuit (Gray/Yellow wire) between EGR solenoid harness connector and terminal No. 40 at PCM C1 harness connector. See Figure . If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Gray/Yellow wire.
  8. If no other possible causes are remaining, replace PCM.
  9. Turn ignition off. Disconnect EGR solenoid harness connector. See Figure . Start engine and let it idle. If engine runs rough or stalls, inspect EGR valve for carbon build-up. Clean as necessary. If EGR valve is clean, replace EGR valve.
  10. Turn ignition off. Disconnect PCM harness connectors. See Figure . Measure resistance between engine ground and control circuit (Gray/Yellow wire) at EGR solenoid harness connector. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground in Gray/Yellow wire.
  11. If no other possible causes are remaining, replace PCM.
scientia non olet · About LEMON Manuals