P0384 code meaning
Glow Plug Control Module 1 Control Circuit High
Powertrain system Generic code P03xx codes Check engine light
What P0384 means
P0384 is the counterpart of P0383: the control line from the engine module to the glow plug control module is too high, i.e. shorted to positive. In GM's logic for the 2010/11 Saab 9-5 2.0 TiD the signal terminal should show 9.5–10.5 V; a higher voltage for more than 0.5 s, with ignition on and 9–16 V, sets the code, there without check engine light. Ford's 2023 diesels (6.7 and 3.0 litre) use P0384 differently from the J2012 name, for the supply voltage of the glow plug module: below 6.5 V, above 16.5 V or open, detected in about 1 s – today J2012 has P052F for that. So with Ford, check battery, alternator and the module's supply first. The consequence is missing or irregular preheating or a protective shutdown of the module, with a poor cold start.
P0384 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 P0384
- No or irregular preheating, hard starting when cold
- Smoke after a cold start
- Warning lamp depending on the manufacturer
Common causes of P0384
- Most likelyControl line chafed against positive or bridged in the connector
- PossibleGlow plug control module faulty internally (feeding back)
- PossibleFord: supply of the module outside 6.5–16.5 V or open (battery, alternator, fuse)
- Less likelyEngine 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 moduleGlow plug supply relay
What each part of P0384 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. |
| 84 | The exact fault in that area. |
What to do next
- Note P0384 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 P0384
What does P0384 mean?
P0384 means "Glow Plug Control Module 1 Control Circuit High". P0384 is the counterpart of P0383: the control line from the engine module to the glow plug control module is too high, i.e. It is a generic code, so it means the same on every make.
Is it safe to drive with P0384?
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 P0384 fail an emissions test?
Yes, it can. P0384 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 P0384 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. This is a job for a workshop.
Will P0384 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.