P0699 Sensor Reference Voltage C Circuit High

P0699 indicates a high condition on Sensor Reference Voltage C circuit. The shared C reference supply is above range or being backfed.

Code details

Generic OBD-II · P0

System: Computer
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace sensors before checking for short-to-voltage or backfeed on the shared C reference circuit.

Symptoms of P0699

Check-engine light, sometimes with several unrelated codes at once.
Warning lights, a no-start, or intermittent electrical faults.
Communication or module-reset problems on a scan tool.

Common causes of P0699

Low battery voltage, poor grounds, corroded connectors, or blown fuses.
Wiring or network (CAN bus) faults between modules.
A module software/programming issue, or rarely a failed controller.

Useful checks before replacing parts

Check reference voltage C at multiple sensors, related signal voltages, controller output, freeze-frame data, and other high-input sensor codes.
Inspect for short-to-voltage faults, open sensor grounds, crossed circuits, damaged harness insulation, water intrusion, and incorrect wiring repairs.
Disconnect branches of the C reference circuit to determine whether a sensor, harness fault, or module output is backfeeding voltage.

Related OBD-II codes

These nearby computer entries can help compare wording and pin down the fault area.