Fuel rail temperature sensor failed internally (short circuit); Sensor signal wire chafed and shorted to ground or to the sensor ground return; Damaged, corroded or wet connector terminals at the sensor or control unit; Sensor integrated with the rail pressure sensor and the combined unit has failed; Fault in the alternative fuel control unit or engine control unit input circuit; Incorrect wiring from a poor previous repair or conversion work.

P01B6

Alternative Fuel Rail Temperature Sensor Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
B6: FaultThe specific fault in that area

What it means

P01B6 means the engine control unit has seen the signal from the alternative fuel rail temperature sensor sit below its expected voltage range. This applies to vehicles running a second fuel such as LPG or CNG alongside petrol. A low voltage usually points to a short to ground in the circuit or a failed sensor. The control unit then cannot trust the gas temperature reading used to calculate fuel quantity.

Symptoms

Engine warning light on
Car runs on petrol only, or will not switch to the alternative fuel
Poor running, hesitation or rough idle on gas
Higher fuel consumption than normal
Difficult starting on the alternative fuel
Other alternative fuel system codes stored alongside

Possible causes

Fuel rail temperature sensor failed internally (short circuit)likely
Sensor signal wire chafed and shorted to ground or to the sensor ground returnlikely
Damaged, corroded or wet connector terminals at the sensor or control unitpossible
Sensor integrated with the rail pressure sensor and the combined unit has failedpossible
Fault in the alternative fuel control unit or engine control unit input circuitrare
Incorrect wiring from a poor previous repair or conversion workrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including engine temperature and fuel mode at the time
Check for other alternative fuel or sensor supply voltage codes, which may point to a shared wiring or supply fault
Visually inspect the sensor, its connector and the wiring loom for chafing, heat damage, pinched wires, corrosion and water ingress
Check live data: compare the alternative fuel rail temperature reading with ambient or coolant temperature on a cold engine; an implausibly high reading suggests a short to ground
With the ignition off and connector unplugged, test the sensor resistance against the manufacturer's specification for the model and engine
With the connector unplugged, check the reference voltage at the harness and test the signal wire for a short to ground
Check wiring continuity between the sensor and control unit, and confirm the ground return is sound
Clear the code and road test to confirm whether it returns; work on gas fuel components should only be done by someone trained on the system, as the fuel is under pressure

How to fix

Replace the fuel rail temperature sensor, or the combined pressure and temperature sensor if that is how it is fitted
Repair or replace the damaged wiring section and secure it away from heat and sharp edges
Clean, repair or replace faulty connector terminals and make sure the seals are seated correctly
Correct any faulty wiring left from earlier repairs or the conversion installation
Replace or repair the control unit only after the wiring and sensor have been proven good, following the manufacturer's procedure

Can I keep driving?

Medium severity

The car can usually keep being driven, often on petrol only, but it should be repaired soon as gas operation may be restricted and running may be affected. If you smell gas or notice any leak, stop and have the system checked before further use.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.