P06A7
Sensor Reference Voltage B Circuit Range or Performance
The 5-volt sensor reference rail B is electrically connected but its voltage is out of tolerance — drifting, sagging under load, or noisy instead of a stable 5.00 V. Every sensor fed from reference B then reports skewed readings, which can trigger secondary faults. Causes: a partial short or high resistance on the reference-B circuit, an overloaded rail caused by a shorted sensor, or an internal regulator fault in the module.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Reference rail driftedCommon
Parts involved
- Sensor Reference Voltage B
P06A7 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.