P1121

Code

LAND ROVER P — Powertrain

Pedal Demand Sensor Performance Range / Performance

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 14 EN: 39 RU: 22

AI status

Completed

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Page language: EN

Causes

Faulty accelerator/pedal demand position sensor (internal fault)
Damaged or corroded wiring or connector (opens, shorts to power/ground, high resistance)
Poor 5V reference or ground at sensor
Sensor signal channel mismatch or out-of-range output (potentiometer wear or contamination)
Intermittent mechanical binding or foreign object affecting pedal travel
ECM/PCM input fault or software issue (rare)

Symptoms

Check Engine Light (MIL) illuminated
Reduced engine power or limp-home mode
Unresponsive or delayed throttle response
Erratic idle or surging when pressing pedal
Inability to accelerate smoothly; sudden drop in power
Stored freeze-frame data showing unusual pedal voltage values

What to check

Read and record all stored DTCs and freeze-frame data with a capable scan tool
Monitor live data for both pedal position channels (often two independent signals) while operating pedal from rest to full travel
Verify presence and stability of 5V reference and ground at pedal sensor connector
Visually inspect pedal assembly, wiring harness, and connectors for damage, corrosion or pin damage
Backprobe the sensor harness and wiggle wires while watching live data for intermittent changes
Compare pedal sensor voltages to throttle body position sensor (if available) during idle and accelerator movement to see correlation issues

Signal parameters

Reference voltage (sensor 5V supply): approx. 4.75–5.25 V
Sensor ground: near 0 V (low resistance to chassis)
Signal channel A (idle to full): typical ≈0.3–1.0 V (idle) to 3.5–4.5 V (wide open) — values vary by model
Signal channel B (redundant) should change monotonically and typically mirror/inverse channel A across range (example: if A rises, B falls or also rises but with different slope depending on design)
Channels should be within manufacturer correlation tolerance and not identical; unexpected jumps, flatlines or values outside 0.1–0.5 V of expected curve indicate fault

Diagnostic algorithm

Use a scan tool to read P1121 plus any related codes; record freeze-frame and live data for both pedal channels and throttle position.
Inspect pedal assembly, connector and wiring for visible damage, corrosion, or loose pins. Repair any physical damage.
With ignition ON (engine off) backprobe the connector: verify 5V reference present, sensor ground continuity to chassis, and both signal voltages. Compare to expected signal_params.
Operate pedal while monitoring both signal channels on the scan tool or multimeter. Look for monotonic smooth change and correct correlation between channels. Note any intermittent behavior when flexing harness.
If reference or ground is out of tolerance, trace and repair wiring to ECM; re-test signals at pedal after repair.
If power/ground OK but a signal channel is out-of-range, test sensor resistance if service data available, or substitute a known-good sensor where practical.
If signals are correct at the pedal but module still reports fault, inspect wiring between pedal and ECM for intermittent open/short using wiggle tests and measure at ECM connector.
Clear codes and perform a controlled test drive to confirm resolution. If fault persists and wiring/sensor verified, consider ECM input failure or software — consult manufacturer bulletins and perform module reflash or replacement per service information.
After repair, ensure no other related DTCs remain and perform final functional test of throttle response and driveability.

Likely causes

Wiring harness damage at pedal (chafe, broken wire, pin pushed out)
Corroded connector terminals causing high resistance in reference or signal
Failed dual-channel pedal position sensor where one channel is out of range or channels do not correlate
Loose or missing sensor ground connection
Contaminated or sticky pedal assembly causing abnormal sensor movement

Fault status

⚠️ Status

P1121 — Pedal Demand Sensor Performance/Range: pedal position sensor signal out of expected range or channels not correlating correctly.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5–2.5 hours

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P1121 — Pedal Demand Sensor Performance Range / Performance