Fuel Temperature Sensor A Circuit High Input
The fuel temperature sensor circuit is reporting a voltage signal that is too high, indicating the sensor may be failed, wiring is shorted, or the PCM is not reading the signal correctly. This affects fuel delivery calculations, particularly in flex-fuel vehicles, and should be repaired promptly to maintain proper engine operation.
What You Might Notice
- Check Engine Light (MIL) illumination
- Incorrect fuel delivery or poor fuel economy
- Engine hesitation or rough idle
- Potential hard starting in cold conditions
- Other fuel composition-related codes present
Most Common Causes
- 1
Faulty fuel temperature sensor
The sensor itself has failed internally, causing it to send an abnormally high voltage signal to the PCM.
- 2
Shorted or damaged wiring/connectors
Wiring to the fuel temperature sensor is shorted to power, or connectors are corroded/loose, causing high circuit voltage.
- 3
Open circuit in sensor wiring
A break in the sensor circuit wiring can cause the signal to default high, triggering the DTC.
- 4
PCM programming error or failure
The powertrain control module may have a software glitch or internal failure causing misinterpretation of sensor signals.
How to Diagnose It
- 1
Check Faulty fuel temperature sensor — The sensor itself has failed internally, causing it to send an abnormally high voltage signal to the PCM.
- 2
Check Shorted or damaged wiring/connectors — Wiring to the fuel temperature sensor is shorted to power, or connectors are corroded/loose, causing high circuit voltage.
- 3
Check Open circuit in sensor wiring — A break in the sensor circuit wiring can cause the signal to default high, triggering the DTC.
- 4
Check PCM programming error or failure — The powertrain control module may have a software glitch or internal failure causing misinterpretation of sensor signals.
How to Fix It
- 1
Test fuel temperature sensor
Use a multimeter to measure the sensor's resistance and voltage output at idle and under load. Compare readings to manufacturer specifications; if out of range, replace the sensor.
- 2
Inspect wiring and connectors
Visually inspect the fuel temperature sensor wiring harness and connector for corrosion, damage, or loose pins. Clean connectors with electrical contact cleaner or replace damaged wiring.
- 3
Check for shorted wiring
Use a multimeter in resistance mode to test for shorts between the sensor signal wire and power or ground. Repair or replace any shorted wiring sections.
- 4
PCM reprogramming or replacement
If sensor and wiring test good, contact the vehicle manufacturer or a dealer to check for PCM software updates. If unavailable or unsuccessful, the PCM may need replacement.
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