What does it mean?
P1374 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: IC Module 3X Reference Circuit Malfunction .
Symptoms
- MIL on, often with other ignition codes
- Hard starting and in some cases a complete no-start
- Cutting out or stalling at low engine speed
- Misfire, rough running and backfire while starting
- Erratic tachometer and poor drivability under load
Likely causes
- Open, shorted or chafed 3X reference wire between the ignition module and the PCM
- Failing crankshaft position sensor feeding the 3X signal
- Damaged reluctor teeth or metal debris stuck on the trigger wheel
- Corroded module connector or a poor ignition module ground
- Ignition control module internal output fault
- Electrical interference from arcing plug leads or a failing coil pack
- PCM reference input circuit fault
How to fix it
- Record all stored codes first, ignition and crank codes together narrow the search
- Inspect the module and PCM connectors and the 3X reference wiring end to end
- Verify the ignition module ground with a voltage drop test and check its supply
- Scope the 3X signal while cranking and while running, looking for dropouts
- Inspect the crank sensor tip, the reluctor wheel condition and the air gap
- Replace arcing secondary ignition leads and route them away from the low voltage harness
- Replace the crank sensor or the ignition control module according to the measurements