P1159

Code

CITROEN P — Powertrain

Electric throttle signal malfunction

Brand: CITROEN

Type: P — Powertrain

Views: UK: 0 EN: 9 RU: 5

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Page language: EN

Causes

Damaged or corroded wiring/connectors between throttle body, accelerator pedal sensor and ECU
Failed throttle body (drive-by-wire) or internal throttle position sensors
Failed accelerator pedal position sensor/module
Poor or missing ground or reference voltage to sensors
Blown fuse or faulty relay supplying throttle electronics
ECM/software fault or intermittent ECU input failure

Symptoms

Check Engine Light (MIL) illuminated
Engine goes into limp mode (reduced power) or limited throttle response
Poor idle or stalling at idle
Lack of throttle response, hesitation or surging
Stored freeze-frame data showing abnormal throttle/pedal values

What to check

Read DTCs and freeze-frame data with a capable scan tool; record related codes
Check for additional related codes (pedal sensor, throttle actuator, supply/ground circuits)
Visual inspection of throttle body and pedal harness for damage, corrosion or water intrusion
Check fuses/relays powering throttle electronics
Measure battery voltage with engine off and running to confirm proper supply
Use scan tool to view live data: accelerator pedal position (APP) and throttle position sensor (TPS) channels and actuator command values

Signal parameters

Reference voltage to sensors typically ≈5.0 V (±0.25 V) — check with backprobe
Sensor output range commonly ≈0.5–4.5 V from closed to wide-open throttle (varies by model)
Battery/system voltage expected ≈11–14.5 V during tests
Dual/duplicate sensors should correlate (two TPS or APP channels): difference between channels should be small and follow expected relationship
No unexpected pulses/shorts to ground or battery on signal/reference lines

Diagnostic algorithm

Connect a full-function scan tool, record all stored and pending codes plus freeze-frame. Note whether MIL forces limp mode.
Inspect visually: connectors, pins, harness routing, signs of heat/corrosion, water entry at the throttle body and pedal module.
Verify battery and charging system voltages. Replace or charge battery if voltage is low (low voltage can cause spurious faults).
With connector connected, monitor live data: observe accelerator pedal position sensors while moving pedal; then observe TPS while commanding throttle (or opening manually if safe). Verify plausible, smooth voltage or percent changes and correct correlation between redundant sensors.
Backprobe sensor reference and signal pins: confirm ~5 V reference, proper ground, and sensor output within expected range (≈0.5–4.5 V).
If reference/ground missing or erratic, trace and repair wiring, check fuses and relays supplying sensors/ECU.
Perform continuity/resistance checks between sensor pins and ECU pins to isolate open/short/intermittent wiring. Wiggle harness while watching live data.
Use scan tool to command/throttle actuate if supported; if throttle does not respond or shows incorrect feedback, suspect throttle body electronics and replace or bench-test per manufacturer procedure.
If wiring and sensors pass but fault persists, consider ECU fault — confirm with manufacturer diagnostic procedures before replacement.
After repair or part replacement, clear codes and perform throttle adaptation/relearn procedure per Citroën service instructions; road test and re-scan for recurrence.

Likely causes

Open/shorted signal or reference wire to throttle position sensor(s)
Intermittent connector corrosion or water ingress at throttle body harness
Faulty throttle body electronics (motor/position sensors)
Failed accelerator pedal module producing implausible sensor correlation
Weak battery/charging system causing out-of-range voltages

Fault status

⚠️ Status

P1159: Electric throttle signal malfunction — ECM detected implausible or missing throttle/pedal/actuator signal. Vehicle may be in limp mode; reduced power and limited throttle response possible.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours

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P1159 — Electric throttle signal malfunction