P0698
Sensor Reference Voltage C Circuit Low
Sensor reference voltage / ECM
Generic OBD-II
High
What it means
P0698 means the ECM's C sensor reference voltage — typically a 5-volt supply shared by several sensors — has dropped too low, usually from a short to ground. Because many sensors depend on that reference, this can trigger multiple sensor codes and make the engine run poorly, enter limp mode, or start hard until the short is found.
High
Can I keep driving? Be cautious — a low sensor reference can knock out several sensors at once, so the engine may run poorly, drop into limp mode, or be hard to start. Get it diagnosed promptly.
Common symptoms
What you'll notice
- Check-engine light on, often with several sensor codes at once
- Rough running, hesitation, or stalling
- Reduced power or limp mode
- Hard starting in some cases
Common causes
Most likely first
- A sensor shorting the shared 5-volt reference circuitLikely
- Damaged or corroded wiring or ground in the reference circuitCommon
- Short to ground in the ECM harnessCommon
- Faulty ECMLess often
How to diagnose & fix
Work through it in order
- Scan and note every sensor that shares reference circuit C.
- Inspect the reference wiring and grounds for shorts, damage, or corrosion.
- Unplug the sensors on that reference one at a time; when the voltage recovers, the last-disconnected sensor is the short.
- Repair the wiring or replace the shorted sensor.
- If the circuit stays low with the sensors disconnected, suspect the ECM.
FAQ
Quick answers
Is it safe to drive with P0698?+
Not ideal — several sensors can lose their reference at once, causing poor running or limp mode. Diagnose it before driving far.
Can I just clear P0698?+
It comes straight back while the reference stays shorted; the shorted sensor or wire has to be found first.
Related codes
Often seen with P0698
Read & clear P0698 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