Code
P1670
FORD
P — Powertrain
Electronic Feedback Signal Not Detected
AI status
Completed
Completed
100%
Causes
- Damaged, corroded or disconnected sensor connector/wiring
- Failed sensor (crank, cam, camshaft position, speed or other feedback sensor)
- Blown fuse or loss of power/ground to sensor or control module
- Faulty PCM/ECM or module that provides reference or reads feedback
- Intermittent open/short in harness or short to voltage/ground
- Aftermarket equipment or recent repairs disturbed wiring or grounds
Symptoms
- Check Engine MIL illuminated
- Engine may crank but not start, or starts then stalls
- No or erratic ignition timing / poor running / reduced power or limp mode
- Starter/crank but no injector/fuel-pulse in some cases
- Other related DTCs for position/sensor circuits may be present
What to check
- Read and record freeze frame and all stored trouble codes with a scan tool; note vehicle state when code set
- Inspect battery voltage and ground connections; ensure good battery charge
- Visually inspect wiring, connectors and sensor mounting for damage, corrosion or loose pins
- Check relevant fuses and relays for power to sensors and control modules
- Verify presence of other related codes (crank/cam/speed) to narrow the circuit
Signal parameters
- Hall-type position sensors: digital square wave 0–5 V (pulses) while cranking/running
- Variable reluctance (VR) sensors: AC sine wave; typical amplitude ~0.2–2.0 VAC depending on speed (increases with rpm)
- Reference voltage from PCM to sensors: nominally 5 V (check for stable 5 V reference at connector)
- Ground: near 0 V; good low-resistance path required
- Frequency: pulses/frequency increases with engine RPM (observe on oscilloscope)
Diagnostic algorithm
- Confirm P1670 is current or historic; note freeze-frame and vehicle conditions when set
- Verify battery voltage >12.4 V at rest and >10 V while cranking; recharge/test battery if low
- Inspect connectors at the suspected sensor(s) and PCM; unclip, check pins for corrosion, bent pins or water intrusion
- Check fuses/relays that supply power/reference to sensors; replace if faulty
- Backprobe sensor connector: verify reference voltage (≈5 V) and ground presence with key ON; if missing, trace back to fuse/PCM
- With appropriate safety, measure sensor output while cranking using a multimeter (AC for VR) or oscilloscope for waveform. Look for pulses or a signal change. If no signal, test continuity from sensor to PCM
- Perform wiggle test on harness while monitoring signal for intermittent faults
- If wiring and power/ground are good but no valid signal, swap in a known-good sensor (if available) and retest
- If new sensor works and wiring is good, clear codes and test-drive to confirm repair
- If replaced sensor does not restore signal and wiring checks out, suspect PCM input circuit; confirm with manufacturer procedures before PCM replacement
- Clear codes and recheck; if code returns, follow advanced module/ECM diagnostic flow in service manual
Likely causes
- Connector corrosion, damaged wiring or poor ground between sensor and PCM
- Failed feedback sensor (crankshaft/camshaft/speed/other)
- Loss of reference voltage or ground to the sensor (fuse, relay, wiring)
- Intermittent harness break or chafing causing open circuit during cranking
- PCM input circuit fault (least likely)
Fault status
Status
Electronic Feedback Signal Not Detected — PCM did not receive expected sensor/feedback signal (missing reference or output). May prevent normal starting/running and can trigger limp mode.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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