Honda Civic P0168: Fuel Temperature Too High diagnosis
Code verification standard
P0168 is published with SAE J2012 / ISO 15031-6 code structure plus Honda Civic diagnostic context.
This page covers meaning, symptoms, first checks, live data, misdiagnosis risk, and repair verification.
What does this mean?
Code P0168 indicates that the Powertrain Control Module (PCM) has detected an excessively high fuel temperature reading from the fuel temperature sensor (FTS), or that the fuel composition is outside the expected parameters. This condition can lead to reduced engine performance, decreased fuel efficiency, and potential damage to fuel system components, especially in diesel engines where fuel temperature directly impacts injection timing and exhaust aftertreatment systems (like DPF regeneration). The FTS typically uses a thermistor to measure fuel temperature, and its resistance changes with temperature, sending a corresponding voltage signal to the PCM. A P0168 code suggests this signal is consistently above the manufacturer's specified maximum threshold.
How serious is this code?
Driving with a P0168 code is generally not immediately dangerous, but it can lead to significant issues over time. High fuel temperatures can reduce engine power, decrease fuel economy, and potentially cause damage to fuel injectors, fuel pumps, and other sensitive fuel system components due to thermal stress and reduced lubrication properties of overheated fuel. In diesel vehicles, excessively hot fuel can also negatively impact the diesel particulate filter (DPF) regeneration process and increase harmful emissions. It's advisable to diagnose and repair this issue promptly to prevent further damage and maintain optimal vehicle performance and longevity.
Diagnostic system: General powertrain circuit
On a Honda Civic, the P0168 code should be diagnosed as part of the general powertrain circuit group. Related codes and live data from this same system can change the repair priority, so avoid replacing parts from the code name alone.
Most Common Causes for Honda Civic
- Faulty fuel temperature sensor
- Clogged or faulty fuel injector
- Damaged, chafed, or broken wiring harness
- Corroded or loose electrical connector
- Vacuum leak in intake system
- PCM/ECM software needs update (TSB)
- Internal PCM/ECM failure
Symptoms to Watch For
- Check Engine Light is illuminated
- Significant loss of engine power
- Difficulty starting the engine
- Rough or unstable idle
- Poor acceleration or sluggish response
- Decreased fuel economy
- Hesitation or stumble during acceleration
Before replacing parts, check these first
- Record freeze-frame data and related codes before clearing the fault.
- Inspect wiring, connectors, vacuum lines, fluid leaks, and fuses tied to the named system.
- Use live data or a multimeter to confirm the failed circuit before replacing parts.
- Check for blown fuses, weak battery voltage, and damaged connectors before buying major parts.
Live data to compare
- Freeze-frame conditions
- Related codes
- Circuit voltage and continuity
How to Diagnose
Common Mistakes
Treating the code description as a parts list instead of verifying the circuit, operating conditions, and related codes. Always confirm the fault with freeze-frame data, live data, visual inspection, and circuit checks before spending money on parts.
Repair verification
After the repair, clear P0168, complete a drive cycle, and confirm the monitor runs without the code returning. Save the before/after scan report if the vehicle needs emissions inspection.
Frequently Asked Questions
Can I drive with the P0168 code?
If the check engine light is solid, you can usually drive to a safe location or mechanic. If the light is flashing, pull over immediately to prevent catastrophic engine or catalytic converter damage.
Will the P0168 code clear itself?
Once the underlying problem is fixed, the engine computer will run its self-checks. If it passes over several drive cycles, the light will turn off automatically. You can also clear it immediately using an OBD2 scanner.
Will this code fail an emissions test?
Yes. If the Check Engine Light is on due to the P0168 code, your Honda will automatically fail an OBD2 plug-in emissions or smog test.
What should I check first for P0168?
Record freeze-frame data and related codes before clearing the fault. Inspect wiring, connectors, vacuum lines, fluid leaks, and fuses tied to the named system. Use live data or a multimeter to confirm the failed circuit before replacing parts.
Join the Discussion
Repair Estimate
Fuse, connector, wiring, cleaning, or basic inspection
Major component replacement after live data and circuit tests confirm failure
Costs vary widely; start with visual inspection and circuit confirmation to avoid unnecessary parts.
DIY Difficulty
Can usually be performed at home with basic hand tools.