P0697
Sensor Reference Voltage C Circuit/Open
Sensor reference voltage (ECM)
Generic OBD-II
High
What it means
P0697 means the ECM detected an open (or out-of-range) condition on its third 5-volt reference circuit, "C." That regulated reference feeds several engine sensors, so when it's lost, multiple sensors read wrong at once — which can make the engine run poorly, drop into limp mode, or set a cluster of related codes.
High
Can I keep driving? Drive with caution — losing a shared 5-volt reference can throw off several sensors at once, causing poor running, limp mode, or stalling; get it diagnosed promptly.
Common symptoms
What you'll notice
- Check-engine light on, often with several sensor codes set at once
- Reduced power or limp mode
- Rough idle, hesitation, or surging
- Possible stalling or hard starting
Common causes
Most likely first
- Open, or a short to ground or power, in the 5-volt reference C wiringLikely
- A shorted sensor pulling the shared reference circuit downCommon
- Corroded or loose connector on the reference circuitCommon
- Faulty ECM/PCM 5-volt reference supplyLess often
How to diagnose & fix
Work through it in order
- Scan for all stored codes — the sensors sharing reference C help pinpoint the circuit.
- Inspect the reference-C wiring and connectors for opens, shorts, and corrosion.
- With the key on, measure the reference voltage (should be about 5V) at the affected sensor connectors.
- Unplug sensors on that circuit one at a time to find one shorting the reference down.
- Only after wiring and sensors check out, consider a faulty ECM/PCM. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0697?+
Not really — the reference voltage feeds multiple sensors, so the engine can run poorly, drop into limp mode, or stall. Have it diagnosed before extended driving.
Can I just clear P0697?+
It returns quickly because the reference circuit is still faulty. Clearing won't restore the sensors that depend on it.
Related codes
Often seen with P0697
Read & clear P0697 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