Fuel temperature sensor faulty or reading out of range; Damaged wiring or poor connector contact on the sensor circuit (short to supply, open circuit or corrosion); Fuel genuinely overheating from heat soak, a hot return line or a heat source close to the fuel lines or rail; Fault in the fuel supply or return system, such as a restricted return line, weak pump or faulty pressure regulation, causing excess heating of the fuel; Faulty or missing cooling for the fuel (where fitted, a fuel cooler or its coolant circuit not working properly); Fault in the engine control unit's sensor input or its software.

P0168

Fuel Temperature Too High.

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
68: FaultThe specific fault in that area

What it means

P0168 is the generic code for fuel temperature too high. The engine control unit has seen a signal from the fuel temperature sensor, or a calculated fuel temperature, that stays above the expected limit. Fuel that is too hot can be less dense and can vaporise, which upsets fuelling and can affect the pump and injectors. Where the sensor is fitted and how the temperature is worked out depends on the model and engine.

Symptoms

Engine warning light on
Hard starting when hot or long cranking after a hot soak
Rough idle or hesitation under load
Poor fuel economy
Loss of power or the engine running in a reduced-power mode
Fuel smell or vapour around the engine bay in hot conditions

Possible causes

Fuel temperature sensor faulty or reading out of rangelikely
Damaged wiring or poor connector contact on the sensor circuit (short to supply, open circuit or corrosion)likely
Fuel genuinely overheating from heat soak, a hot return line or a heat source close to the fuel lines or railpossible
Fault in the fuel supply or return system, such as a restricted return line, weak pump or faulty pressure regulation, causing excess heating of the fuelpossible
Faulty or missing cooling for the fuel (where fitted, a fuel cooler or its coolant circuit not working properly)possible
Fault in the engine control unit's sensor input or its softwarerare

How to diagnose

Read the stored codes and freeze frame data, noting engine temperature, ambient conditions and load when the fault set, and check for other fuel or sensor codes.
Check the live fuel temperature reading with the engine cold and compare it with the coolant and intake air temperatures; a cold engine should show similar values.
Inspect the sensor wiring and connector for chafing, heat damage, water ingress and corrosion, and check for any related technical service information for the model.
Check the sensor circuit for supply, earth and signal against the manufacturer's data, and test the sensor resistance at different temperatures if the data is available.
Watch the fuel temperature as the engine warms and while driving to see if it climbs genuinely or jumps suddenly, which points to a sensor or wiring fault.
Check the fuel supply and return lines for kinks, restrictions or heat damage, and look for heat sources or missing heat shields near the fuel system.
Check the fuel pressure and pump operation against specification, as the correct procedure depends on the engine and fuel system.
Where a fuel cooler is fitted, check its operation and the related coolant flow as per the model's workshop data.

How to fix

Replace the fuel temperature sensor if it reads incorrectly or fails testing.
Repair or replace damaged wiring and connectors on the sensor circuit.
Restore any missing or damaged heat shielding and correct any routing that places fuel lines close to hot components.
Repair or replace restricted fuel return lines, a failing pump or a faulty pressure regulator as the testing shows.
Repair the fuel cooling system, where fitted, including its coolant circuit.
Update or repair the control unit only if testing shows an input fault or a known software issue for that model.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but get it checked soon as genuinely hot fuel can cause poor running and strain on the fuel system. Avoid heavy loads or long journeys if the car loses power or runs badly.

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