P2128

Code

LAND ROVER P — Powertrain

Pressure regulator / pedal position sensor / switch E input high

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 25 EN: 38 RU: 32

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Page language: EN

Causes

Open, damaged, or shorted wiring in the sensor E signal/power circuit
Corroded, loose, or contaminated connector at the pedal position/pressure regulator sensor
Failed pedal position sensor (APP) or related pressure regulator/switch component
Short to battery voltage (12V) on the signal circuit
Poor or missing ground for the sensor
Intermittent damage from water ingress or chafing harness

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced engine power or limp-home mode
Poor or erratic throttle response
Throttle/pedal pedal position readings out of range in live data
Possible no-start or hesitation under acceleration if ECM protects system

What to check

Read and record all stored DTCs and freeze-frame data with a scan tool
Inspect sensor and wiring harness visually for damage, pin corrosion, loose terminals, or water ingress
Check for Technical Service Bulletins (TSBs) or model-specific service notes
Backprobe sensor connector with key ON and compare actual voltages against specifications
Perform a wiggle test on wiring while watching live data to check for intermittent faults
Check sensor supply (reference) voltage and ground circuits for proper continuity

Signal parameters

Typical reference: 0–5.0 V signal range (varies by model)
‘Input high’ usually detected when signal > ~4.5 V or equals battery voltage
Reference (VBATT) supply usually ~5 V or regulated reference ~0–5 V depending on sensor type
Ground continuity should be near 0 Ω; supply should be stable at expected reference voltage

Diagnostic algorithm

Connect a capable scan tool, record codes, freeze-frame and live APP/pressure-sensor data. Clear codes and attempt to reproduce.
Visually inspect sensor, harness and connectors for damage, corrosion, or water. Repair any obvious issues.
With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage, signal voltage, and ground presence. Compare to specification. If signal reads battery voltage, suspect short to 12V.
Perform continuity tests: check for short to battery on the signal wire and for short to ground on the reference wire. Repair any shorted wiring.
Wiggle the harness/connectors while observing live data to find intermittent faults. Inspect routing — look for chafing or pinched wires.
If wiring and connectors pass, substitute a known-good sensor (if available) or bench-test the sensor per manufacturer procedure.
If the replacement sensor corrects the code, reassemble and road-test. If not, inspect ECM connector pins and continuity to ECM. Consider ECM testing or replacement only after wiring and sensor are confirmed good.
After repairs, clear codes and verify no reappearance under varied operating conditions.

Likely causes

Short to 12V on sensor/signal wire (most common for 'input high')
Failed pedal position sensor (or pressure regulator switch) producing high output voltage
Damaged or corroded connector causing intermittent high readings
Loose or missing sensor ground raising signal voltage

Fault status

⚠️ Status

ECM detected excessively high voltage on the Pressure Regulator / Pedal Position Sensor E input circuit. Possible causes: short to battery, faulty sensor, poor ground, or damaged connector/wiring.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 3.0 hours

Repair manuals

Manual library for LAND ROVER

320

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

LAND ROVER

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P2128 — Pressure regulator / pedal position sensor / switch E input high