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.

Real-world scan data

Seen in

14,957

scans in the past year

Found in

2.4%

of scans

4.2%

of scans that found faults

Appears alongside · share of P0683 scans

P0110in 29.3% of scans

P0100in 22.6% of scans

C1057in 12.3% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P0683 yourself

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

▶ Get it on Google Play

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