What Does P0168 Mean?
The ECM has detected that the fuel temperature is excessively high, exceeding the maximum threshold defined by the manufacturer. High fuel temperatures reduce fuel density and can cause vapor lock, poor combustion, reduced power, and potential fuel system damage. This is commonly seen in hot climates, during heavy towing, or with fuel return line issues. The driver may notice hard starting when hot, reduced power, and rough idle.
Common Causes
30%
Restricted or kinked fuel return line causing fuel to recirculate and heat up
25%
Fuel cooling system failure (on equipped vehicles) or missing heat shields
20%
Faulty fuel temperature sensor providing an incorrect high reading
15%
Fuel pump operating at excessive pressure, generating heat in the fuel
10%
Prolonged heavy load driving in extreme ambient temperatures
Diagnostic Steps
1
Monitor fuel temperature PID in live data. Compare the reading to actual fuel temperature measured with an infrared thermometer at the fuel rail. A large discrepancy suggests a faulty sensor.
2
Inspect the fuel return line for kinks, restrictions, or collapsed sections. On diesel vehicles, check the return line flow rate by disconnecting it at the tank and measuring volume returned over time.
3
Check for missing or damaged heat shields between the exhaust system and fuel lines. Verify fuel line routing has not been altered to run too close to exhaust components.
4
Measure fuel pressure at the rail. Excessive pressure can indicate a stuck fuel pressure regulator, which forces the pump to work harder and generates heat.
5
If the vehicle has a fuel cooler, inspect it for blockage, leaks, or proper coolant flow through the cooler circuit.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The ECM has detected that the fuel temperature is excessively high, exceeding the maximum threshold defined by the manufacturer. High fuel temperatures reduce fuel density and can cause vapor lock, poor combustion, reduced power, and potential fuel system damage. This is commonly seen in hot climate...
The most common cause of P0168 (Engine Fuel Temperature Too High) is: Restricted or kinked fuel return line causing fuel to recirculate and heat up
Typical repair costs for P0168 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Exercise caution. Excessively hot fuel can cause vapor lock leading to stalling, and in extreme cases poses a fire risk if fuel lines or seals are degraded. Avoid heavy towing or high-load driving until resolved. Diesel vehicles may experience significant power loss.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0168 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
