What it means
Fuel temperature exceeds the safe maximum. Risk of fuel pump damage and injection imprecision.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The fuel temperature sensor reports the temperature of fuel to the engine control module, which uses it to account for changes in fuel behavior. P0168 sets when the reported fuel temperature exceeds the module’s calibrated safe limit, whether the fuel is genuinely hot or the sensor signal is inaccurate.
Common causes
Most likely first.
- Fuel temperature sensor reading incorrectly
- Fuel cooling system not working effectively
- Restricted fuel return or circulation
- Fuel overheated by an external heat source
Symptoms
- Check engine light on
- Hard starting or rough running
- Reduced engine performance
- Fuel odor or vapor near the vehicle
How to diagnose it
- Use a scan tool to record freeze-frame data and compare fuel temperature with ambient and engine temperatures before starting, since a hot reading on a cold vehicle points toward a sensor or circuit issue.
- Check the fuel temperature reading as the engine warms and look for an implausible jump or persistently high value.
- Inspect the fuel temperature sensor, connector, and wiring for damage, corrosion, loose contact, or heat exposure.
- Check for restricted fuel return or circulation and signs that a nearby heat source is warming the fuel.
- Test the sensor circuit and sensor response against the manufacturer's specification before replacing parts.
Common fixes
- Repair a loose, corroded, or damaged fuel temperature sensor connector or wiring.
- Replace a fuel temperature sensor that fails testing.
- Restore fuel circulation by clearing a confirmed restriction in the return or supply path.
- Repair a confirmed fuel cooling fault or shield fuel lines from an identified heat source.
Can I keep driving?
Avoid hard acceleration and long trips while fuel temperature remains high or the engine runs poorly, because overheating can impair fueling and damage the pump. Stop if you smell fuel or see vapor, and have the vehicle checked before continuing.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.