Fault code P0380 – a step-by-step guide to diagnosing and fixing it

Error code P0380 is displayed and the check engine light is on - what does this mean?

DTC P0380 is set by the OBD/EOBD system when a problem is detected in the glow plug heater A control circuit. This fault code mainly affects diesel vehicles and indicates a fault in the glow plug system, which is responsible for preheating the engine at cold temperatures.

What causes can this fault code have?

• Defective glow plugs
• Damaged glow plug relay
• Blown fuse in the glow plug circuit
• Corroded or loose cable connections
• Defective glow plug control unit
• Broken cables to the glow plug system
• Faulty glow plug ground wire
• Defective temperature sensor for the glow plug system

What symptoms occur in parallel with fault code P0380?

• Starting problems in cold temperatures: The vehicle is difficult or impossible to start, especially at low outside temperatures
• Extended starting time: The engine takes significantly longer to start than usual
• Unsteady idling: The engine runs rough and unstable after a cold start
• White smoke from the exhaust: White or blue smoke appears, especially during a cold start
• Check engine light: The warning light on the dashboard lights up continuously
• Reduced engine power: Noticeable loss of power, especially when the engine is cold

How to fix the problem of fault code P0380?

• Repairing fault code P0380 requires a systematic diagnosis of the glow plug system.
• Check glow plugs individually and replace defective ones: Measure the resistance of each glow plug and replace the corresponding glow plug if it deviates from the set value (usually 0.6-2 Ohm)
• Test the glow plug relay and replace if necessary: Check the relay for proper function by measuring the voltage and continuity; if defective, replace the entire relay
• Check and replace fuses in the glow plug circuit: Visually and electrically check all relevant fuses, replace blown fuses and determine cause of overload
• Completely check the glow plug system wiring: Inspect all cables for breaks, corrosion and loose connections, repair or replace damaged cables
• Diagnose and replace the glow plug control unit: Check the control unit with a diagnostic device, replace the control unit if there are errors in the internal memory or no communication
• Clean and tighten the ground connections: Clean all glow plug earth connections, remove corrosion and tighten connections to the correct torque