P0383 code meaning
Glow Plug Control Module 1 Control Circuit Low
Powertrain system Generic code P03xx codes Check engine light
What P0383 means
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.
P0383 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0383
- No preheating, poor cold start
- Smoke after a cold start
- Warning lamp depending on the manufacturer
Common causes of P0383
- Most 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)
- Less likelyDriver in the engine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Glow plug control module 1Module wiringEngine control module
What each part of P0383 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3 | Area: ignition system or misfire. |
| 83 | The exact fault in that area. |
What to do next
- Note P0383 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0383
What does P0383 mean?
P0383 means "Glow Plug Control Module 1 Control Circuit Low". Many diesels have a separate glow plug control module that the engine module commands over a control line. It is a generic code, so it means the same on every make.
Is it safe to drive with P0383?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0383 fail an emissions test?
Yes, it can. P0383 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0383 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P0383 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.