Failed glow plug on the affected cylinder; Damaged or corroded electrical connector at the glow plug; Open or shorted glow plug wiring harness; Faulty glow plug control module or relay; Blown fuse or poor ground connection in the glow plug circuit; Engine control module software or internal fault (rare)

DTC codes / P03xx · Ignition system and misfire / P0382

P0382Glow Plug/Heater Circuit 'B'

Q: What does code P0382 mean?

Glow Plug/Heater Circuit 'B'. P0382 indicates that the engine control module has detected a fault in the glow plug or heater circuit designated as 'B', which typically serves a specific cylinder or bank on diesel engines. The computer monitors the circuit's electrical characteristics and sets this code when the voltage or current falls outside the expected range during the glow plug's activation period.

P0382 indicates that the engine control module has detected a fault in the glow plug or heater circuit designated as 'B', which typically serves a specific cylinder or bank on diesel engines. The computer monitors the circuit's electrical characteristics and sets this code when the voltage or current falls outside the expected range during the glow plug's activation period.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Hard starting or rough idle when the engine is cold
Excessive white smoke from the exhaust after a cold start
Longer cranking times before the engine fires
Reduced fuel economy during warm-up
Misfire or stumbling shortly after a cold start

Common causes, most likely first

Failed glow plug on the affected cylinder
Damaged or corroded electrical connector at the glow plug
Open or shorted glow plug wiring harness
Faulty glow plug control module or relay
Blown fuse or poor ground connection in the glow plug circuit
Engine control module software or internal fault (rare)

How to diagnose and fix it

Scan all modules for stored codes and record freeze-frame data to confirm the fault is current
Visually inspect the glow plug, connector, and wiring for damage, corrosion, or looseness
Measure the resistance of the suspect glow plug and compare it to the manufacturer's specification
Check for battery voltage and ground at the glow plug connector during the glow plug activation period
Test the glow plug control module and relay for proper operation and continuity
Repair or replace any damaged wiring, connectors, or the faulty glow plug as needed
Clear the codes and verify the repair by performing a cold-start test and rechecking for pending codes

Don't overlook the glow plug control module

A glow plug that tests good on a bench may still fail under load, so always check circuit voltage drop while the plug is commanded on.
Corroded connectors at the glow plug tips are a frequent cause of P0382 that visual inspection alone can miss.
The code can be set by a faulty glow plug control module even when all individual glow plugs test within specification.
On some vehicles, a weak battery or charging system can trigger glow plug circuit codes due to low voltage during cranking.
P0382 specifically refers to circuit 'B', so confirm which cylinder or bank that corresponds to before replacing parts.

Can I keep driving with P0382?

You can generally drive the vehicle, but cold starting may be difficult and prolonged driving with a faulty glow plug can lead to carbon buildup or further electrical damage. Avoid heavy loads and extended idling until the fault is repaired.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.