Code
P0184
HUMMER
P — Powertrain
Fuel Temperature Sensor 1 Circuit Intermittent
AI status
Completed
Completed
100%
Causes
- Loose, corroded or contaminated sensor connector
- Damaged, chafed or broken wiring in the sensor harness
- Poor or intermittent ground or reference voltage to the sensor
- Faulty fuel temperature sensor (internal intermittent)
- Water intrusion or corrosion at connector
- Connector pins pushed out or poor crimp
Symptoms
- Intermittent MIL (Check Engine Light) illumination
- Fuel temperature PID shows erratic or jumping values on a scan tool
- Occasional rough idle, hesitations, or temporary drivability issues
- Incorrect fuel trim adjustments or slightly reduced fuel economy
- Possible failed emissions test when fault is active
What to check
- Retrieve freeze frame and DTC status with a scan tool; note conditions when code set
- Monitor live fuel temperature PID while performing a wiggle test on harness and connector
- Visually inspect sensor connector for corrosion, water, push-out pins, or bent terminals
- Inspect wiring harness for chafe, kinks, repairs, or pinched sections along the route
- Backprobe connector and measure signal voltage, reference voltage (usually ECU-supplied) and ground continuity
- Measure sensor resistance at ambient and after warming (compare to expected behavior)
Signal parameters
- Sensor type: typically an NTC thermistor (resistance decreases as temperature rises)
- Expected behavior: smooth, gradual change in resistance/voltage with temperature — no rapid jumps
- Typical signal voltage span (varies by vehicle): ~0.5–4.5 V depending on temperature and ECU circuit
- Typical resistance behavior (vehicle-specific): higher ohms at low temp, lower ohms at high temp; consult OEM spec for exact Ω vs °C values
- Intermittent fault: signal may show momentary spikes, dropouts to open-circuit (infinite Ω) or shorted values
Diagnostic algorithm
- Use a scan tool to view live fuel temperature PID and freeze frame data. Note when the code sets and any correlated conditions (load, temp, vibration).
- Visual inspection: disconnect battery if required by vehicle procedure. Inspect sensor body, connector, and harness for corrosion, moisture, physical damage or loose pins.
- Wiggle test: backprobe the sensor connector and monitor the PID or signal voltage while gently wiggling the harness and connector to reproduce the intermittent condition.
- Measure resistance of the sensor at ambient and after warming (remove harness if needed). Verify resistance changes smoothly with temperature. Compare to OEM specification.
- With key on (engine off) or per OEM procedure, backprobe sensor harness: verify reference voltage (if used), signal voltage range, and ground integrity. Look for intermittent loss of reference or grounding.
- Check continuity and insulation of wiring from sensor to PCM. Repair any open, short to ground/power, or high-resistance connections. Pay attention to any harness sections that move or sit near heat/chafe points.
- Clean or replace corroded connector terminals. Secure harness and apply dielectric grease if appropriate for the connector type.
- If wiring and connector are good and sensor fails resistance/voltage checks or remains intermittent, replace the fuel temperature sensor and retest.
- If problem persists after sensor replacement, inspect PCM connector and test for intermittent inputs; consider PCM diagnostics per OEM procedure.
- Clear codes and perform a road/drive cycle to verify the fault does not return.
Likely causes
- Corroded connector or wet/loose terminal at the sensor
- Wire chafe or intermittent break in harness (movement/wiggle-dependent)
- Failed fuel temperature sensor
- Poor ground or intermittent reference voltage from the PCM
Fault status
Status
Intermittent fault detected on Fuel Temperature Sensor 1 circuit. The controller logged a non-continuous irregularity in the sensor signal (open, short, or erratic reading). May not be present during every system check.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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