Fuel Temperature Sensor B Circuit High Input
The fuel temperature sensor circuit is reporting a voltage level that is too high, indicating the sensor may be faulty or the circuit has an electrical problem. This prevents the engine computer from accurately measuring fuel temperature, which affects fuel injection timing and delivery strategy, particularly in flex-fuel vehicles.
What You Might Notice
- Check Engine Light (MIL) illuminated
- Rough idle or hesitation during acceleration
- Poor fuel economy
- Difficulty starting the engine
- Other fuel composition-related diagnostic codes present
Most Common Causes
- 1
Faulty fuel temperature sensor
The sensor itself may be defective and sending an artificially high voltage signal to the PCM, causing the circuit high condition.
- 2
Damaged wiring or connectors
Open, shorted, or corroded wiring between the sensor and PCM can cause the circuit to read high voltage, or a loose connector can create intermittent high readings.
- 3
Defective ambient or intake air temperature sensor
A malfunctioning auxiliary temperature sensor can affect fuel temperature calculation and trigger this code in certain vehicle systems.
- 4
PCM programming error or module failure
Rarely, a corrupted PCM calibration or failing powertrain control module can misinterpret sensor signals as high voltage.
How to Diagnose It
- 1
Check Faulty fuel temperature sensor — The sensor itself may be defective and sending an artificially high voltage signal to the PCM, causing the circuit high condition.
- 2
Check Damaged wiring or connectors — Open, shorted, or corroded wiring between the sensor and PCM can cause the circuit to read high voltage, or a loose connector can create intermittent high readings.
- 3
Check Defective ambient or intake air temperature sensor — A malfunctioning auxiliary temperature sensor can affect fuel temperature calculation and trigger this code in certain vehicle systems.
- 4
Check PCM programming error or module failure — Rarely, a corrupted PCM calibration or failing powertrain control module can misinterpret sensor signals as high voltage.
How to Fix It
- 1
Test and replace fuel temperature sensor
Use a multimeter to test the sensor's resistance and voltage output. If readings are out of specification, replace the sensor with a new one and retest.
- 2
Inspect and repair wiring and connectors
Check the wiring harness between the fuel tank and PCM for damage, corrosion, or loose connections. Repair or replace damaged wiring and reseat connectors firmly.
- 3
Check related temperature sensors
Test the ambient air temperature and intake air temperature sensors for proper operation. Replace any sensors that are reading out of range.
- 4
Clear code and perform system retest
After repairs, clear the diagnostic trouble code using a scan tool and perform a complete fuel system test cycle to confirm the circuit voltage is now within normal range.
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