What does it mean?
P1312 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Ignition control module (ICM) - ignition coil secondary coil signal, circuit 2 .
Symptoms
- MIL (check engine lamp) on
- Misfire that appears mainly under load and on acceleration, smoother at light throttle
- Rough idle, hesitation and a general lack of power
- Popping in the exhaust and a fuel smell
- Hard starting in damp weather, sometimes with visible arcing at night
Likely causes
- Coil with a failed or high-resistance secondary winding on circuit 2
- Cracked coil boot, carbon-tracked plug well or arcing to ground before the plug fires
- Spark plug worn with an excessive gap, which raises the required firing voltage
- Damaged, open or high-resistance high-tension lead where separate leads are used
- Feedback wire between the coil pack and the ignition control module open or shorted
- Failed ignition control module
- Moisture in the plug well after washing or a leaking gasket
How to fix it
- Check the misfire counters and freeze frame to identify which cylinder circuit 2 serves
- Inspect the coil boot and plug well for carbon tracks, oil and moisture
- Remove the spark plug, measure the gap and look for signs of a weak or intermittent spark
- Measure coil primary and secondary resistance and compare with specification
- Test the feedback wire between the coil and the module for continuity and shorts
- Substitute a known-good coil and see whether the fault follows it
- Replace the ignition control module only after the coil, plug, lead and wiring have all been cleared