P0699: Sensor Reference Voltage C Circuit High
What to do
Expect reduced power, and treat it as worth prompt attention — an over-voltage reference can damage the sensors connected to it, turning one wiring fault into several real ones.
What this code means
Reference voltage C is above its expected value — a reference wire touching a higher supply, or a failed regulator inside the module. The last of P06xx's decimal-numbered slots; the block runs on into its hexadecimal ones from P069A.
As with the other over-voltage reference faults, the sensors on the circuit are built for five volts and may be receiving twelve, so finding this promptly limits how many genuinely damaged sensors have to be replaced afterwards.
Likely causes
Start here
- Reference wire shorted to battery voltage · moderate
- Chafed harness against engine or bracket · moderate
Less common
- Failed control 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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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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