CASE 010
Diesel Hard Starting When Cold
advanced
22 min
Diesel
Vehicle
- ModelTraining Estate 1.5
- Engine1.5 dCi
- Mileage174,000 km
Customer complaint
The engine is difficult to start when cold, with grey-white smoke and rough running for a few seconds.
History
Glow plugs were replaced 18 months ago. Service interval is overdue.
Fault codes
P0380 Glow plug/heater circuit A
Live data
- Coolant temperature at cold startAgrees with ambient
- Rail pressure during crankingReaches requested value slowly
Measurements
- Glow plug resistanceOne plug open circuit
- Glow plug current drawLow on one module
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Diagnostic case
Next step — Reasoning.
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Confirmed cause
One or more glow plugs faulty, causing poor cold combustion, grey-white smoke and hard starting.
Reasoning
Cold-only hard starting with white smoke is characteristic of inadequate cold-start assistance or low compression. An open glow plug plus a glow circuit code confirms the cold-start side; rail-pressure build-up should also be checked because slow pressure rise can contribute.
Recommended repair
- Replace the faulty glow plug(s).
- Check the glow plug control module and circuit.
- Verify cold start and smoke after repair, and service the vehicle.
Related OBD codes
All values shown are training examples. Real thresholds depend on the manufacturer, engine, temperature and system — always confirm with the vehicle service documentation.