What does the P0168 code mean?
The P0168 is a generic OBD-II powertrain trouble code. Its official definition is “Fuel Temperature Too High“.
When you connect a vehicle code reader to the diagnostic link connector, the powertrain control module (PCM) reports P0168 if it detects that the fuel temperature has exceeded a calibrated maximum threshold (typically above 140–160 °F depending on the vehicle). The fuel temperature sensor is usually a thermistor mounted on the fuel rail, in the fuel tank, or along the fuel supply line. As fuel temperature rises, fuel density decreases and vaporization characteristics change, requiring adjustments to injection timing and quantity. If the PCM sees a fuel temperature reading that is unreasonably high or that exceeds the sensor’s normal operating range, it sets P0168. Some manufacturers (such as Ford) may label this code as “Fuel Temperature Sensor Circuit High Input”, but the SAE J2012 generic definition is “Fuel Temperature Too High”. Using a professional car scanner with live data allows technicians to view the actual fuel temperature value and compare it to engine coolant temperature and ambient temperature. An obd2 scanner can also display the sensor voltage and check for related codes. Unlike codes like P0183 which indicate a high input from the sensor circuit itself, P0168 indicates the measured fuel temperature is genuinely too high.
Symptoms of Error Code P0168
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine power or limp mode activation
- Poor fuel economy due to altered injection strategy
- Hard starting, especially after hot soak
- Engine knocking or pinging under load
- Possible fuel odor or vapor lock symptoms
Main Causes of Error Code P0168
- Excessive fuel temperature due to hot engine operation (extreme driving conditions, turbocharger heat soak)
- Restricted fuel return line causing fuel to recirculate and overheat
- Faulty fuel temperature sensor reporting erroneously high readings
- Clogged fuel cooler (on vehicles equipped with one)
- Low fuel level combined with high ambient temperature (fuel in tank absorbs more heat)
- Aftermarket modifications affecting fuel system cooling
How to Diagnose Error Code P0168?
- Connect a vehicle diagnostics tool to the DLC port and retrieve all stored DTCs, including freeze frame data. Note fuel temperature reading, engine coolant temperature, and ambient temperature.
- Perform a visual inspection of the fuel system components: fuel lines, fuel cooler (if equipped), and fuel temperature sensor wiring. Look for crushed or kinked fuel return lines.
- Start the engine and let it idle. Use a car code scanner with live data to monitor the fuel temperature value. Compare it to engine coolant temperature. Normal fuel temperature should be close to ambient or slightly warmer (up to 130 °F). If it reads above 170 °F while coolant is still cool, the sensor may be faulty.
- Allow the engine to reach operating temperature and drive under load. Monitor fuel temperature. If it rapidly climbs above 180–200 °F, there may be a restriction in the fuel return system.
- Check the fuel cooler (if equipped) for airflow blockage, debris, or fan operation.
- Disconnect the fuel temperature sensor and measure its resistance at known temperatures. Compare with manufacturer specifications. If the sensor reads incorrectly, replace it.
- Inspect the fuel return line for kinks, collapses, or blockages. A restricted return line causes fuel to bypass back to the tank without cooling, raising overall fuel temperature.
- Clear the code with an obd2 scanner after repairs and perform a test drive under various loads to verify the fix.
Possible Causes and Diagnostic Methods
| Possible Cause | How to Check? |
| Faulty fuel temperature sensor | Measure resistance at known temperature; compare to specs |
| Restricted fuel return line | Visually inspect for kinks; perform fuel pressure/flow test |
| Clogged fuel cooler | Check for debris blockage; verify cooling fan operation |
| Low fuel level + high ambient temp | Fill fuel tank; monitor temperature after refueling |
| Extreme driving conditions | Review freeze frame data; check for towing or track use |
| PCM misinterpretation | Update PCM software if TSB exists |
Tools needed: obd2 scanner or vehicle diagnostics tool, digital volt/ohmmeter (DVOM), fuel pressure gauge, infrared thermometer, wiring diagram, basic hand tools, safety glasses.
How do I fix error code P0168? (Solutions to the Problem)
Simple Fixes
- Clear the code with a car code scanner and drive under normal conditions. If the code does not return, it may have been triggered by extreme heat soak (e.g., after a long highway climb).
- Ensure the fuel tank is at least half full to improve fuel cooling capacity.
- Check and clean the fuel cooler fins (if visible) from debris.
In-depth Diagnosis and Repair Solutions
- Replace the fuel temperature sensor if it is reading incorrectly. Use an OEM sensor for accurate readings.
- Repair or replace a kinked or collapsed fuel return line. Ensure the line is routed away from hot exhaust components.
- Replace a clogged fuel cooler or repair its mounting/fan assembly.
- If the fuel return system is restricted internally (e.g., blocked fuel pressure regulator), replace the regulator or fuel pump module as needed.
- Install an aftermarket fuel cooler if the vehicle is used for heavy towing or track driving and lacks adequate cooling.
- Apply a PCM software update if a manufacturer TSB addresses high fuel temperature thresholds.
Fix faults based on symptoms
| Observed Symptom | Likely Root Cause | Recommended Action |
| Fuel temperature high only under heavy load | Restricted fuel return or inadequate cooling | Inspect return line; upgrade fuel cooler |
| Fuel temperature reads high at idle with cold engine | Faulty sensor | Replace fuel temperature sensor |
| Fuel temperature high after refueling | Hot fuel from station or low tank level | Fill tank; monitor; if persistent check sensor |
| Code returns after sensor replacement | Underlying mechanical restriction | Check fuel return line and cooler thoroughly |
Common Error Code P0168 in Vehicles
Ford & Lincoln: On Ford F-150, Super Duty, and Lincoln Navigator with EcoBoost engines, P0168 often occurs during heavy towing in hot weather. The fuel temperature sensor is located on the high-pressure fuel rail. Ford TSB 22-1122 recommends installing an auxiliary fuel cooler kit for vehicles used in severe duty applications. A restricted fuel return line near the frame rail is a known issue on 2017–2020 models.
General Motors (Chevrolet, GMC, Cadillac): GM defines P0168 as “Fuel Temperature Too High”. Common on Silverado, Tahoe, and Escalade with 6.2 L engines. The fuel temperature sensor is integrated into the fuel pump module. GM TSB PIP5821 addresses fuel temperature issues caused by low fuel level combined with high ambient temperatures. Keeping the tank above 1/4 full is recommended.
Ram (Dodge, Jeep, Chrysler): Ram 1500 with 5.7 L HEMI may log P0168 when the fuel temperature sensor in the tank reads excessively high. Chrysler TSB 09-001-21 recommends inspecting the fuel pump module for a stuck-open bypass valve that prevents fuel from circulating through the cooler.
Toyota & Lexus: Toyota Tundra and Lexus LX 570 with V8 engines sometimes see P0168 during sustained high-speed driving in desert climates. The fuel temperature sensor is located on the fuel rail. Toyota recommends ensuring the radiator cooling fan operates correctly, as insufficient airflow can raise underhood temperatures.
Honda & Acura: Honda Pilot and Acura MDX with V6 engines may experience P0168 when the fuel return line is pinched during underbody repairs. Inspect the line routing after any recent service work. Honda TSB 23-067 suggests checking for aftermarket skid plates blocking airflow to the fuel cooler.
Volkswagen & Audi: VW Touareg and Audi Q7 with TDI engines may log P0168 when the fuel cooler becomes clogged with debris. The cooler is mounted near the front bumper and can accumulate leaves and mud. Cleaning the cooler and restoring airflow typically resolves the issue.
BMW & Mini: BMW X5 and 5 Series with diesel engines sometimes store P0168 due to a faulty fuel temperature sensor in the fuel filter housing. Replacing the entire fuel filter assembly (which includes the sensor) is the recommended fix.
P0168 Frequently Asked Questions
Can I drive with a P0168 code?
You can drive short distances, but prolonged operation with high fuel temperature can cause engine damage, including detonation (knocking) and fuel system component failure. The PCM may reduce power to protect the engine. It is best to diagnose and repair promptly, especially if you notice reduced performance.
How much does it cost to fix P0168?
Costs vary widely depending on the root cause. Replacing a fuel temperature sensor costs $100–$300. Repairing a restricted fuel return line costs $150–$400. Installing an auxiliary fuel cooler can cost $500–$1,200. Using a vehicle diagnostics tool to pinpoint the exact cause before purchasing parts can save significant expense.
Will replacing the fuel temperature sensor always fix P0168?
Not necessarily. If the fuel temperature is genuinely too high due to a mechanical restriction (kinked return line, clogged cooler), replacing the sensor will not solve the problem. The new sensor will still report high fuel temperature. Always verify the actual fuel temperature using an infrared thermometer on the fuel rail or line before condemning the sensor.
What is considered “too high” fuel temperature?
Most manufacturers consider fuel temperatures above 158–176 °F (70–80 °C) as too high. Gasoline begins to vaporize aggressively above these temperatures, causing vapor lock and injection issues. Diesel fuel can degrade above 194 °F (90 °C). Check your vehicle’s service manual for specific thresholds.
Can low fuel level cause P0168?
Yes. When the fuel tank is low, the remaining fuel absorbs more heat from the exhaust system and ambient underbody temperatures. The fuel has less volume to dissipate heat, causing temperature to rise. Keeping the tank above 1/4 full, especially in hot weather, can prevent this code.
How do I reset the P0168 code after repair?
Use an obd2 scanner to clear the code. Then perform a drive cycle that includes idling, steady cruising, and a moderate load (hill climb or acceleration). The PCM will monitor fuel temperature during this cycle. If the repair was successful, the MIL should stay off. Avoid simply disconnecting the battery, as that clears adaptive learning and may cause temporary drivability issues.
Is P0168 a serious code?
Moderately serious. While it will not immediately disable the vehicle, high fuel temperature can lead to engine knocking, reduced power, and potential fuel system damage. Early diagnosis with a car scanner is recommended.
P0168 Related OBD2 Errors
- P0180 – Fuel Temperature Sensor A Circuit Malfunction
- P0181 – Fuel Temperature Sensor A Circuit Range/Performance
- P0182 – Fuel Temperature Sensor A Circuit Low Input
- P0183 – Fuel Temperature Sensor A Circuit High Input
- P0187 – Fuel Temperature Sensor B Circuit Low Input
- P0188 – Fuel Temperature Sensor B Circuit High Input
- P0190 – Fuel Rail Pressure Sensor Circuit Malfunction
- P0191 – Fuel Rail Pressure Sensor Circuit Range/Performance
- P0087 – Fuel Rail/System Pressure Too Low
- P0088 – Fuel Rail/System Pressure Too High
Important Warning
Important! Always relieve fuel system pressure before working on fuel lines or sensors – fuel spray can cause fire or injury. Wear safety glasses and work in a well-ventilated area. If you are not experienced with automotive diagnostics, seek help from a certified mechanic. Using a quality obd2 scanner and following manufacturer-specific procedures ensures accurate results and prevents unnecessary part replacements.