P0383Glow Plug Control Module 1 Control Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- Many diesels have a separate glow plug control module that the engine module commands over a control line. P0383 means this line is too low. In GM's logic for the 2010/11 Saab 9-5 2.0 TiD the engine module drives the module with a PWM signal and holds about 10 V on the line at rest (9.5–10.5 V at the signal terminal); if it reads too little voltage for more than 0.5 s – short to ground, or an open circuit or high resistance – it sets P0383, with ignition on, 9–16 V, once per ignition cycle. In that European version the code does not turn on the check engine light. Without a valid command the module does not glow, so the engine starts poorly when cold. Ford uses P0384 differently and not P0383; GM's 2016/2018 diesels have their output stages in the engine module and no such line. For US vehicles there is no code-specific source.
- What you may notice
- No preheating, poor cold start
- Smoke after a cold start
- Warning lamp depending on the manufacturer
- Likely causes
- LikelyControl line between engine module and glow plug module shorted to ground or open
- PossibleCorroded connector at the glow plug module in the engine bay
- PossibleGlow plug control module faulty (input pulls the line down)
- RareDriver in the engine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.