Code
P0727
GWM
P — Powertrain
- No signal from engine speed sensor
AI status
Completed
Completed
100%
Causes
- Failed engine speed/crankshaft position sensor
- Open, shorted or corroded wiring or connector in the sensor circuit
- Damaged or missing reluctor/tooth wheel on crankshaft
- Poor sensor air gap or magnetic interference
- Blown fuse or missing sensor power/ground
- Faulty PCM/TCM or poor instrument cluster input
Symptoms
- No or erratic engine RPM reading on dash or scan tool
- No-start or hard start, intermittent stalling
- Transmission abnormal shifting, stuck in limp/low gear
- Illuminated MIL/Check Engine light
- Diagnostic trouble codes related to crank/cam sensors or transmission speed
What to check
- Confirm code with scan tool and review freeze frame/other stored codes
- Visual inspection of sensor, connector and wiring for damage, corrosion, or oil/water contamination
- Check fuses and power/ground circuits related to the sensor and control modules
- Backprobe the sensor connector and measure supply voltage and ground
- Measure sensor output with a DVOM while cranking and with an oscilloscope to view waveform
- Wiggle test wiring while observing live data for intermittent changes
Signal parameters
- Hall-effect sensor: square wave, 0–5 V (or 0–12 V on some systems), frequency proportional to RPM
- Variable reluctor (magnetic) sensor: AC sine/oscillating waveform, amplitude typically ~0.2–2.0 VAC at idle up to several volts at higher rpm
- Typical open-circuit DC resistance for VR sensors: a few ohms to several hundred ohms (manufacturer-specific)
- Supply/reference: commonly 5 V or 12 V for active sensors; verify against vehicle wiring diagram
- Signal frequency: multiplies with engine speed (check expected pulses per revolution from service data)
Diagnostic algorithm
- Verify the presence of P0727 and note any related codes (P0320, P0340, P0720, etc.).
- Perform a visual inspection of the sensor, connector, and wiring harness for damage, corrosion, or contamination.
- Check for proper sensor supply voltage and ground at the sensor connector with key ON (refer to vehicle wiring diagram for expected values).
- Backprobe the signal wire and measure output while cranking or running: use a DVOM for presence/voltage and an oscilloscope to confirm waveform and frequency.
- If no output, test sensor resistance (if applicable) and compare to specification. Wiggle harness while testing to detect intermittent faults.
- Inspect the reluctor/tooth wheel and sensor air gap; correct any mechanical damage or excessive gap.
- Repair any wiring faults (repair harness, replace connector terminals), replace sensor if electrical tests fail, or replace reluctor if damaged.
- If wiring and sensor OK, check module grounds and inputs; substitute or bench-test control module only after exhausting sensor/harness fixes.
- Clear codes and perform a road test/run to verify the repair and that the engine speed signal is stable under load.
Likely causes
- Broken sensor connector or pushed-out terminal
- Wire insulation chafed where it flexes near the engine or transmission
- Sensor failed internally (no output during crank/run)
- Reluctor ring damaged, missing teeth, or loose timing wheel
- Open or shorted reference power or ground to the sensor
- Short to voltage or ground at the signal circuit
Fault status
Status
P0727 — Engine speed sensor circuit: no signal (engine RPM not detected).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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