OBD-II code · Powertrain (generic)
P0668 Control Module Internal Temperature Sensor A Circuit Low
Same as P0666 with the signal voltage below the plausible range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Is it safe to drive with P0668?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelySensor internal short
- Less likelyConnector pins corroded - high contact resistance
- Less likelyHarness chafing through insulation
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 2–6 h
- Emissions test
- Usually unaffected
- Parts involved
- Ecu Internal Temperature Sensor A
Related codes
- P06ADControl Module Internal Temperature Sensor B Circuit Low
- P0665Intake Manifold Tuning Valve Control Circuit High Bank 2
- P0666Control Module Internal Temperature Sensor A Circuit
- P0667Control Module Internal Temperature Sensor A Range or Performance
- P0669Control Module Internal Temperature Sensor A Circuit High
- P066ACylinder 1 Glow Plug Control Circuit Low
- P066BCylinder 1 Glow Plug Control Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.