P0683

Glow Plug Control Module 1 to PCM Communication Circuit

Glow plug control / communication Generic OBD-II Medium

What it means

P0683 means the powertrain control module and the glow plug control module have lost proper communication over their shared circuit. On a diesel, the glow plug module manages preheating for starting, so this fault typically shows up as disabled glow plugs and hard, rough, or smoky cold starts rather than a warm-running problem.

Medium

Can I keep driving? Usually yes — the engine runs, but the glow plug system may not preheat properly, so cold starts can be slow, rough, or smoky.

Common symptoms

What you'll notice

Glow plug or check-engine light on
Hard or slow starting in cold weather
Rough running and white smoke on a cold start
Glow plug system not preheating as it should

Common causes

Most likely first

Open, shorted, or damaged wiring between the glow plug module and PCMLikely
Corroded or loose connector at either moduleCommon
Faulty glow plug control moduleCommon
Faulty PCM (less common)Less often

How to diagnose & fix

Work through it in order

Scan and confirm P0683, noting any glow plug module codes.
Inspect the communication wiring and connectors between the glow plug module and PCM for damage, corrosion, or looseness.
Check power and ground to the glow plug control module.
Repair wiring/connectors first; replace the glow plug control module if it fails to communicate.
Re-flash or replace the PCM only after the wiring and module are ruled out.

FAQ

Quick answers

Is it safe to drive with P0683?+

Usually — the engine still runs, but the glow plug system may be disabled, hurting cold-weather starting. Get it checked before winter.

Can I just clear P0683?+

It returns as soon as the PCM loses communication with the glow plug module again; the wiring or module must be fixed.

Related codes

Often seen with P0683

P0670Glow Plug Control Module 1 Control Circuit P0383Glow Plug Control Module 1 Control Circuit P0384Glow Plug Control Module 1 Control Circuit P0381Glow Plug/Heater Indicator Control Circuit

Read & clear P0683 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

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✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX