P01B4
Alternative Fuel Rail Temperature Sensor Circuit
Generic electrical fault on alternative fuel rail temperature sensor (CNG/LPG/H2 systems).
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Sensor failedCommon
Parts involved
- Alt Fuel Rail Temp Sensor
- Sensor Wiring
P01B4 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.