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 status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Computer
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

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.

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 fault area. They may share the same verification status as the source database.