P06A4
Sensor Reference Voltage D Circuit Low
Sensor reference voltage
Generic OBD-II
High
What it means
P06A4 means the engine computer sees a lower-than-expected voltage on its "D" 5-volt sensor reference supply. Several sensors share this reference, so a low reading — usually a short to ground or a failed sensor pulling it down — can set multiple sensor codes at once and force the engine into a reduced-power mode. It rarely stops the car outright but should be diagnosed promptly.
High
Can I keep driving? Often drivable but unpredictable — the low reference can knock out several sensors at once and push the engine into limp mode, so get it diagnosed soon.
Common symptoms
What you'll notice
- Check-engine light on, often with several sensor codes set together
- Rough running, hesitation, or reduced power
- Reduced-power or limp mode
- Intermittent stalling in some cases
Common causes
Most likely first
- A sensor shorting the shared 5-volt reference to groundLikely
- Short to ground or chafed wiring in the reference D circuitCommon
- Corroded or loose connector on the reference circuitCommon
- Internal ECM/PCM fault on the reference D supplyLess often
How to diagnose & fix
Work through it in order
- Scan for all stored codes — sensors sharing reference D usually set codes together and point to the shared circuit.
- Unplug sensors on that reference one at a time to see if the voltage recovers, isolating a shorted sensor.
- Inspect the reference wiring for chafing or a short to ground and check connectors.
- If wiring and sensors are good, the ECM/PCM reference supply is suspect. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P06A4?+
Sometimes short term, but because it can disable several sensors at once and trigger limp mode, get it diagnosed soon.
Can I just clear P06A4?+
It will return until the shorted sensor or wiring on the reference D circuit is repaired.
Related codes
Often seen with P06A4
Read & clear P06A4 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