Code
P1189
Other
P — Powertrain
Pump Speed Signal Fault
AI status
Completed
Completed
100%
Causes
- Faulty pump speed sensor (Hall, VR, or magnet pickup)
- Damaged, corroded, or loose wiring or connector between sensor/pump and PCM/ECM
- Faulty pump control module or pump driver
- Intermittent supply voltage or poor ground to sensor or pump module
- Electromagnetic interference/noise on the signal circuit
- Mechanical failure of the pump (stalled or irregular speed)
Symptoms
- Malfunction Indicator Lamp (MIL) on
- Engine may have reduced power, hesitation, surging or stalling
- Hard starting or no-start condition if pump speed is not reported
- Irregular or low fuel pressure, drivability problems
- Possible activation of limp mode or reduced engine performance
What to check
- Read and record freeze-frame and all stored DTCs and pending codes
- Inspect pump speed sensor connector and wiring for corrosion, bent pins, water intrusion, chafing or damage
- Check battery voltage and main grounds with key on/engine off
- Scan live data: observe pump speed signal, fuel pressure, and related parameters while cranking and running
- Backprobe sensor and ECM connector pins to verify signal presence and voltage reference
- Perform a wiggle test on harness while monitoring signal for intermittent faults
Signal parameters
- Signal type: typically a digital pulse (Hall-effect) or AC sine (variable reluctance) depending on sensor type
- Voltage: Hall-effect/square wave commonly approx. 0–5 V; VR sensors produce low-voltage AC (may be ~0.1–1.5 VAC)
- Behavior: frequency or pulse rate increases with pump speed; waveform should be stable and consistent while engine/pump speed is steady
- Expected characteristics: clean waveform with consistent amplitude and duty cycle; no missing pulses or excessive noise
Diagnostic algorithm
- Retrieve DTCs and freeze-frame; note operating conditions when fault set.
- Visually inspect sensor, pump assembly, wiring harness, and connectors; repair obvious damage.
- With key on, measure reference voltage and ground at the sensor connector; compare to expected values for that vehicle.
- Monitor live data while cranking/idle/run: observe pump speed signal, fuel pressure, battery voltage and related sensors.
- Use a scope to view the pump speed waveform at the sensor and at the ECM to locate where the signal is lost or distorted.
- Perform continuity and resistance checks on signal, power and ground circuits between the sensor/pump and ECM; repair any opens, shorts or high resistance.
- If wiring and connectors are good but no/erratic signal remains, test/replace the pump speed sensor or pump control module per manufacturer instructions.
- After repairs, clear codes and road test; confirm the signal, fuel pressure and drivability are normal and code does not return. Follow vehicle-specific safety and fuel-system procedures when servicing.
Likely causes
- Damaged connector or wiring to the pump speed sensor
- Failed pump speed sensor or pickup
- Low battery or poor ground causing signal dropout
- Faulty pump control module or driver stage
Fault status
Status
P1189 — Pump Speed Signal Fault: ECM detected missing/invalid pump speed signal; MIL set.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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