Fuel Temperature Sensor Circuit High
The fuel temperature sensor is reading higher than expected.
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What it means (plain English)
The fuel temperature sensor should measure the fuel temperature in the line, usually around 60-80 degrees Fahrenheit. If it’s reading too high, it could mean a sensor is faulty or the wiring is damaged.
What the computer is actually seeing
The engine control module (ECM) sees the fuel temperature sensor voltage at around 4.5V, while it should be around 1-2V for normal operation.
What a healthy reading looks like
Normal fuel temperature should be between 60-80°F (16-27°C), with voltage output from the sensor typically 1-2 volts when at normal temperature.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connector of the fuel temperature sensor for damage or corrosion. Decision: If damaged, repair or replace wiring/connector. If not, proceed to step 2.
- 22. Test the fuel temperature sensor with a multimeter. Check resistance across the sensor while heating to see if it varies as expected. Decision: If the sensor is out of spec, replace it. If it tests fine, proceed to step 3.
- 33. Check the fuel temperature against the engine's operating conditions to ensure it's not an engine-related overheating issue. Decision: If the fuel is operating within normal temperatures, and the sensor is fine, inspect the ECM for faults.
Common causes
- Faulty fuel temperature sensor
- Damaged wiring or connectors
- Short circuit in the sensor circuit
- Engine overheating issues
- Incorrect fuel temperature sensor installed
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with SPN 3185 active?
It's moderate severity; you can drive it, but fixing it soon is recommended to avoid further issues.
Will the code come back after clearing it?
If the underlying issue is not resolved, the code is likely to return.
Why would I see this code with other fuel system codes?
Multiple codes can indicate a broader problem impacting the fuel system, like overheating or faulty sensors.
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