P0168
UniversalThe Engine Control Module (ECM) has detected that the engine fuel temperature sensor input signal indicates a fuel temperature that is exceeding a calibrated high limit.
Medium SeverityThis code signifies that the vehicle's computer has detected an excessively high temperature in the fuel system. This can lead to decreased engine performance and potentially reduced fuel efficiency if not addressed.
⚠️ Before You Begin (Safety First)
Always allow the engine and fuel system to cool completely before attempting any work. Disconnect the battery to prevent accidental starts. Be extremely cautious when working with fuel lines, as fuel is highly flammable. Wear appropriate personal protective equipment (PPE) such as safety glasses and gloves. Beware of hot fuel, which can cause severe burns.
Common Symptoms
- Check Engine Light illumination
- Reduced engine power or acceleration
- Decreased fuel economy
- Rough idle or engine stumbling
- Difficulty starting the engine
- Engine stalling
Common Causes
- Faulty fuel temperature sensor
- Damaged or corroded wiring/connector to the fuel temperature sensor
- Restricted fuel return line causing fuel to overheat
- Malfunctioning fuel pump causing excessive fuel pressure and heat
- Engine Control Module (ECM) fault (less common)
Frequently reported on: 2006-2010 Ford F-250/F-350 (6.0L/6.4L Power Stroke), 2007-2012 Dodge Ram 2500/3500 (6.7L Cummins), 2007-2010 Chevrolet Silverado 2500HD/3500HD (6.6L Duramax), 2009-2013 Volkswagen Jetta TDI, 2007-2013 BMW 335i (N54/N55 engine)
Diagnostic Steps
- Connect an OBD-II scanner to confirm the P0168 code and check for any other related codes.
- Locate the fuel temperature sensor (often integrated into the fuel pump assembly or fuel rail) and visually inspect its wiring and connector for any signs of damage, corrosion, or loose connections. Repair as needed.
- Using a multimeter, test the resistance of the fuel temperature sensor. Compare readings to manufacturer specifications. Resistance should change with temperature.
- If possible, check fuel pressure and verify that the fuel return line is not restricted, ensuring proper fuel flow and cooling.
- If the sensor tests faulty or shows intermittent readings, replace the fuel temperature sensor. Ensure the new sensor is compatible with your vehicle.
- Clear the DTCs from the ECM and test drive the vehicle to see if the code returns.
👨🔧 When to Call a Professional
While inspecting and replacing the fuel temperature sensor can often be a DIY task, if the code persists or if you suspect a more complex fuel system issue such as a restricted return line or a failing fuel pump, it is best to consult a professional mechanic. Fuel system diagnostics can be intricate and require specialized tools.
Commonly Asked Questions
What does the P0168 code mean?
The P0168 code indicates that your vehicle's Engine Control Module (ECM) has detected that the fuel temperature in the system is too high, exceeding the manufacturer's specified limits.
Is it safe to drive with a P0168 code?
While your vehicle may still operate, it's generally not recommended to drive for extended periods with a P0168 code. High fuel temperatures can lead to reduced engine performance, decreased fuel efficiency, and potentially cause damage to fuel system components over time.
How do I diagnose a P0168 code?
Begin by inspecting the fuel temperature sensor and its wiring for any damage or loose connections. You can also test the sensor's resistance with a multimeter. Beyond the sensor, check for proper fuel pressure and ensure there are no restrictions in the fuel return line.
Can a bad fuel temperature sensor cause other problems?
Yes, a faulty fuel temperature sensor can send incorrect readings to the ECM, leading to improper fuel mixture adjustments. This can result in symptoms like poor acceleration, reduced fuel economy, rough idle, and even engine stalling.
How expensive is it to fix a P0168 code?
The cost to fix a P0168 code varies. If it's just a faulty fuel temperature sensor, the part itself is usually inexpensive (typically $20-$100), but labor costs can range from $100-$300 depending on the sensor's accessibility. If the issue is a more complex fuel system problem, costs could be higher.