P0699
Sensor Reference Voltage C Circuit High
Sensor reference voltage
Generic OBD-II
High
What it means
P0699 means the ECM sees its "C" 5-volt sensor reference reading higher than expected. Many sensors — throttle, pedal, pressure, and others — share this regulated reference, so when it drifts high those sensors report wrong values and the engine can run poorly or drop into limp mode. The fault usually traces to one shorted sensor, a wiring short to voltage, or the ECM, rather than to the engine itself.
High
Can I keep driving? It can run rough or drop into limp mode, because several sensors share this 5-volt reference — get it diagnosed before relying on the vehicle.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power or limp mode
- Several sensor codes stored at once (they share the same 5-volt reference)
- Rough running, hesitation, or erratic gauges
Common causes
Most likely first
- A sensor on the 5-volt reference C circuit shorted internally, pulling the reference highLikely
- Reference wire shorted to battery or another voltage sourceCommon
- Poor ECM ground or corroded connector affecting the referenceCommon
- Faulty ECMLess often
How to diagnose & fix
Work through it in order
- Scan and note every code present — the sensors sharing reference C help pinpoint the affected circuit.
- Identify the sensors fed by the 5-volt reference C circuit for this vehicle, then unplug them one at a time to see if the reference voltage returns to normal — that isolates a shorted sensor.
- Inspect the reference wiring and connectors for a short to voltage, and check the ECM grounds.
- If the reference stays high with all sensors disconnected and wiring good, the ECM is at fault.
FAQ
Quick answers
Is it safe to drive with P0699?+
Not ideally — because multiple sensors share this reference, the engine can run poorly or derate. Have it diagnosed promptly.
Can I just clear P0699?+
It returns until the shorted sensor or wiring is repaired. Because several sensors share the circuit, a scan tool is the fastest way to isolate the cause.
Related codes
Often seen with P0699
Read & clear P0699 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX