P0683

Glow Plug Control Module to PCM Communication Circuit

Severity: Low
Driving: Drivable — book it in

A fault in the communication circuit between the glow plug control module and the engine control module. The two cannot exchange information, so the engine module cannot confirm the glow plugs are working or tell the glow plug module when to run them.

Possible causes

CommonWiring or connector fault between the two modules
CommonCorroded connector
CommonLow battery voltage
PossibleFailed glow plug control module
PossibleBlown fuse

What you might notice

Hard starting when cold
White smoke on a cold start
Rough running for the first minute from cold
Glow plug light behaving oddly
No symptom at all in warm weather
Glow plug warning light on

What to check, in order

Check battery voltage and state of charge first.
Inspect the connectors at both modules.
Check the wiring between them for damage.
Test the glow plugs themselves as well - a communication fault and a failed plug often arrive together on a high-mileage engine.

Read this code from your own car

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Where this code sits

B · Body C · Chassis P · Powertrain U · Network and communication

Computer output circuits and control module