Code
P2139
Generic
P — Powertrain
Throttle/Pedal Position Sensor/Switch D/F Voltage Correlation
Views:
UK: 16
EN: 32
RU: 19
AI status
Completed
Completed
100%
Causes
- Faulty throttle body position sensor(s) or accelerator pedal position sensor(s) (one or both).
- Damaged, corroded, or loose wiring/connectors between sensors and the ECU.
- Short to battery or ground on one of the sensor signal wires.
- Internal throttle body or pedal mechanical fault producing incorrect sensor movement.
- Poor sensor reference voltage (5 V) or sensor ground.
- ECU input circuit fault (rare).
Symptoms
- Check Engine MIL illuminated (DTC P2139 stored).
- Reduced engine power or limp-home/torque-limited mode.
- Poor throttle response, hesitation, or surging.
- Engine may idle poorly or stall in severe cases.
- Intermittent faults that can occur with vibration or connector movement.
What to check
- Read freeze frame and stored data with a scan tool; note conditions when the fault set.
- Retrieve live PIDs for both sensor channels (D and F) and observe at key-on, closed throttle, and wide-open throttle.
- Visually inspect connectors and wiring for damage, corrosion, bent pins, or moisture at throttle body and pedal assembly.
- Backprobe sensor signal, reference (5 V) and ground circuits; confirm stable reference voltage and good ground.
- Perform wiggle test on wiring and connectors while observing live sensor signals for intermittent changes.
- Check for related codes (shorts, open circuits, other throttle/pedal codes).
Signal parameters
- Reference voltage: nominally 5.0 V (should be stable, typically 4.8–5.2 V).
- Sensor outputs at rest (closed throttle / pedal released): commonly ~0.2–1.0 V (varies by design).
- Sensor outputs at wide-open: commonly ~4.0–4.8 V (varies by design).
- Both sensor channels should change smoothly and have a consistent linear relationship; difference between channels should normally be small (often
- Look for signal noise, dropouts, or one channel fixed while the other moves.
Diagnostic algorithm
- Connect a capable scan tool and confirm P2139 is current or historic; note freeze frame and related codes.
- With ignition on (engine off), monitor both sensor voltages (D and F). Verify stable ~5 V reference and good ground at the sensors.
- Slowly operate the pedal (or manually move throttle plate if safe) and confirm both sensor outputs vary smoothly and proportionally. Log values at closed, mid, and wide-open positions.
- If one sensor is erratic, compare against the known-good sensor curve. If both are erratic, suspect shared reference/ground or wiring harness.
- Visually inspect and if needed disconnect connectors and inspect pins for corrosion, damage, or push-back. Repair or clean as required.
- Perform a wiggle test on harness while observing live data to find intermittent wiring faults.
- If wiring and connectors check good, measure resistance or voltage at the ECU connector for the sensor circuits to isolate sensor vs harness. Repair broken/shorted wiring as found.
- Replace the failed sensor (pedal or throttle body sensor) if bench/voltage tests identify an out-of-spec sensor. Re-test to confirm correlation restored.
- If sensors and wiring are confirmed good but fault persists, consider ECU input/module fault — consult advanced diagnostics or OEM procedures before replacing the ECU.
- Clear codes and perform a road test under the same conditions that set the code. Re-scan to confirm repair.
Likely causes
- Intermittent or corroded connector at the throttle body or pedal sensor.
- Damaged or chafed signal wire causing intermittent open/short or cross-talk.
- Failed pedal position sensor or throttle position sensor (one side out of tolerance).
- Weak/failed sensor reference (5 V) or ground connection.
- Less likely: ECU input channel failure.
Fault status
Status
Voltage correlation between throttle/pedal position sensor circuits D and F is outside expected tolerance. ECU may limit throttle control (reduced power/limp mode) until the condition is corrected.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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