Code
P1337
PEUGEOT
P — Powertrain
Cylinder 1 ignition fail malfunction
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EN: 1
RU: 1
AI status
Completed
Completed
100%
Causes
- Faulty ignition coil (coil pack or coil-on-plug) on cylinder 1
- Worn, fouled, cracked or incorrect spark plug in cylinder 1
- Damaged wiring or poor connector contact to the coil or spark plug
- Faulty ignition driver/module or ECM output for cylinder 1
- Failed or clogged fuel injector for cylinder 1
- Low compression or mechanical engine problem on cylinder 1
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or vibration, especially at idle
- Reduced engine power and acceleration
- Higher-than-normal fuel consumption
- Possible backfire, hesitation, or misfire felt under load
- Failed emissions test (increased hydrocarbons)
What to check
- Read stored DTCs and freeze frame data with a scanner; note misfire counters and engine RPM at fault
- Check for related codes (P0301, P0300, P0351, sensor/timing codes)
- Visual inspection of coil-on-plug, spark plug, wiring harness and connectors for damage, oil, corrosion or loose pins
- Confirm correct cylinder numbering on the specific vehicle before swaps or tests
- Measure coil primary and secondary resistance per manufacturer specs
- Check fuel rail pressure and inspect/operate injector for cylinder 1 (active test or balance test)
Signal parameters
- Coil primary voltage and current/dwell time for cylinder 1 (compare to other cylinders)
- Coil secondary (spark) waveform amplitude and duration
- Ignition driver command (ECM command pulse/duty) for cylinder 1
- Cylinder 1 misfire count and misfire ratio from live data
- Crankshaft speed fluctuation (ΔRPM) when cylinder 1 should fire
- Injector pulse width for cylinder 1 and relative fuel delivery
Diagnostic algorithm
- Connect a good scan tool and record DTCs, freeze frame and live misfire counters. Note engine conditions when fault occurred (load, rpm, temperature).
- Perform visual inspection: remove coil-on-plug and spark plug; inspect for oil, carbon tracking, cracked boot, loose connector or corrosion.
- Swap cylinder 1 ignition coil with a coil from another cylinder and erase codes. If fault moves to the other cylinder (e.g., P03xx for that cylinder), the coil is likely faulty.
- Inspect and wiggle the coil harness and connector while monitoring live data/scan tool for changes. Repair or replace damaged wiring/connector.
- Measure coil primary and secondary resistances and compare to spec. If out of spec, replace coil.
- Use an oscilloscope to check primary and secondary waveforms for irregularities (weak spark, truncated wave, no pulse).
- Check fuel injector operation on cylinder 1: use an injector actuator or scope to confirm injector is pulsing and performing. Perform an injector balance or cylinder contribution test if available.
- If electrical tests are normal, perform a wet/dry compression test or leak-down test on cylinder 1 to rule out mechanical causes.
- Check cam/crank sensor signals and timing correlation if misfire includes timing mismatch codes or no-spark events.
- Verify good battery voltage, engine grounds and power supply to ignition circuits; repair grounding or power issues.
- After repairs, clear codes and perform a road test under similar conditions to confirm the fault does not return. Re-scan for pending or permanent codes.
Likely causes
- Ignition coil fault on cylinder 1 (most common)
- Spark plug worn or fouled
- Damaged coil harness/connector or poor electrical connection
- Faulty injector or fuel delivery issue to cylinder 1
- Low compression or valve/timing problem (less common)
Fault status
Status
P1337 recorded when the engine control module detects an ignition failure or misfire event on cylinder 1. The MIL will be set and diagnostic data (misfire counts, freeze frame) stored. Further electrical, fuel and mechanical testing is required to isolate the root cause.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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