P1586

Code

LAND ROVER P — Powertrain

Malfunction of the accelerator position unit

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 18 EN: 27 RU: 24

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Page language: EN

Causes

Faulty accelerator pedal position sensor (APP) assembly
Damaged wiring harness, broken wires, chafing or pinched connector
Corroded or poorly seated connector terminals
Open or short to power/ground on sensor supply or signal circuits
Faulty body/engine control module (ECM/PCM) or internal electronics
Incorrect calibration or software issue requiring reflash

Symptoms

Check Engine MIL illuminated
Poor throttle response or delayed throttle
Engine enters limp/reduced power mode
Cruise control unavailable
Possible unexpected stall or failure to accelerate as commanded
Fault present while pressing accelerator or intermittently

What to check

Read and record freeze-frame data and all stored DTCs with a capable scan tool
Check for stored pending or historical codes related to APP or throttle circuits (P01xx/P02xx/P21xx/P213x family)
Inspect accelerator pedal connector and wiring for damage, corrosion or water ingress
Backprobe pedal sensor connector and measure supply voltage (5V ref), ground continuity and signal outputs while operating pedal
Compare sensor 1 and sensor 2 live values — they should move proportionally (often one ramps up while the other ramps down)
Check for continuity/short to battery + and ground on signal wires with harness disconnected

Signal parameters

Sensor supply: typically 5 V reference from ECU (check factory data for exact value)
Signal outputs: commonly in the ~0.5 V (rest) to ~4.5 V (full pedal) range — varies by design
Dual sensors usually show correlated but distinct profiles (one increases while the other decreases or both increase proportionally)
Expected steady values with smooth change when pedal is moved — abrupt jumps, dropouts or identical stuck values indicate fault
CAN/serial messages: APP data published at regular intervals to powertrain module — missing or implausible messages will set codes

Diagnostic algorithm

Connect an OBD-II scan tool capable of live data for Land Rover and read all codes and freeze-frame. Note any related codes.
With key on (engine off), visually inspect pedal area, connector and wiring for damage, corrosion, moisture or rodent damage. Repair as needed.
Backprobe the pedal connector: verify ECU 5 V reference present and stable, good ground, and measure the sensor output voltages at rest and while slowly depressing the pedal. Record values.
Compare the two APP sensor outputs (if dual sensors). They should correlate according to factory pattern (one rising while the other falls or both rise at a fixed ratio). If signals are identical, fixed or out-of-range, suspect sensor or wiring.
Check continuity from pedal connector to ECU connector for signal, reference and ground wires. Check for short to battery + or chassis ground.
Wiggle-test the wiring harness while monitoring live data to find intermittent faults.
If wiring and connectors are good, replace or bench-test the accelerator pedal assembly per service procedure. After replacement, clear codes and perform any required throttle/pedal relearn or module adaptation.
If new pedal does not clear the fault, suspect ECU input circuit or ECU failure — perform module diagnostics and consult manufacturer service documentation for further ECU testing or replacement and software updates.
After repairs, verify driveability, confirm DTC does not return and recheck live APP data under driving conditions.

Likely causes

Defective accelerator pedal position sensor or internal sensor failure
Corroded/loose connector at the pedal harness
Short or open in the pedal sensor signal or 5 V reference/ground circuit
Failed ECM input or intermittent wiring fault

Fault status

⚠️ Status

Malfunction of accelerator position unit — accelerator pedal position sensor circuit is reporting implausible or missing data. Check pedal assembly, wiring/connectors and ECU inputs; vehicle may be in limp mode.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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P1586 — Malfunction of the accelerator position unit