P1123

Code

LAND ROVER P — Powertrain

Pedal demand sensor High input circuit

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 16 EN: 20 RU: 19

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Page language: EN

Causes

Open, short to battery voltage, or short to high on the pedal sensor signal circuit
Faulty accelerator pedal position (pedal demand) sensor/assembly
Poor or corroded connector or wiring (pins pushed out, water ingress)
Damaged insulation causing intermittent shorts when harness is moved
Faulty or missing sensor reference/ground at the pedal or ECU
Faulty engine control module (rare) or incorrect ECU programming

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced engine power or limp-home mode
Reduced or no throttle response from accelerator pedal
Cruise control disabled
Possible intermittent or erratic throttle behavior
Fault code P1123 stored in ECU

What to check

Retrieve freeze frame and live data with a scan tool; note pedal sensor voltages/percentages
Visual inspection of pedal sensor connector and wiring for damage, corrosion, or pin push-out
Back-probe pedal sensor connector with ignition ON (engine OFF) to measure signal and reference voltages
Wiggle test wiring/connector while monitoring live data to reproduce fault or intermittent behavior
Check continuity and resistance between pedal connector and ECU connector for the signal, reference, and ground circuits
Check for related codes (TPS, throttle actuator, CAN communications) that might indicate broader issues

Signal parameters

Reference voltage (Vref): typically ~5.0 V with ignition ON (check service data for exact value)
Signal output: variable 0.5–4.5 V across pedal travel (manufacturer-specific; compare to live data/repair manual)
High-input condition: signal significantly above expected range (e.g., >4.5 V) or stuck near battery voltage
Ground: low resistance to vehicle chassis ground
Note: exact voltages and sensor pinout vary by model year — confirm with Land Rover service manual

Diagnostic algorithm

Verify the code and capture freeze frame/live data. Note actual signal voltage(s) reported by the ECU for the pedal sensor.
Attempt to reproduce the fault. Clear codes and monitor while operating the pedal through full travel.
Visually inspect pedal assembly, connector, and wiring harness for damage, water entry, or corrosion. Repair obvious issues.
With ignition ON (engine OFF), back-probe the pedal connector: confirm reference voltage (~5 V), ground continuity, and signal voltage. Observe signal while moving pedal.
If signal is high, disconnect the pedal sensor and re-check the signal at the harness side. If the high voltage remains at harness without sensor connected, suspect short to battery or ECU issue.
Check continuity between pedal connector and ECU connector for signal, reference and ground. Repair any open or shorted wiring (replace damaged sections, repair connectors).
If wiring and connectors are good, replace the pedal demand sensor/assembly. Use OEM or equivalent part.
After repairs, clear codes and perform a test drive or reproduce conditions to ensure the fault does not return. Re-scan for related codes and perform any required relearns/calibrations per service procedures.
If fault persists after sensor and wiring repairs, consider ECU diagnostics or replacement and consult Land Rover technical service information.

Likely causes

Failing pedal position sensor
Short to 12V on the signal wire (connector damage or pin contact issue)
Poor ground or reference voltage at pedal
Wiring harness damage near pedal or steering column

Fault status

⚠️ Status

Engine MIL ON. ECU detected pedal demand sensor signal higher than expected (out-of-range/high). Vehicle may enter reduced-power (limp) mode and disable cruise control until the fault is resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

Similar codes

Repair manuals

Manual library for LAND ROVER

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Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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P1123 — Pedal demand sensor High input circuit