P0668: Control Module Internal Temperature Sensor A Circuit Low
What to do
Usually driveable with no symptom.
What this code means
The module's internal temperature signal is below its plausible range. An internal fault with no external test point, though as with all the module-internal codes the supply and earths are worth confirming before the module is condemned.
Likely causes
Start here
- Failed control module · specialist
Less common
- Low system voltage disrupting communication · moderate
- Water ingress into module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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