Code
DF975
RENAULT
D
-> P2120 - Pedal potentiometer circuit track 2
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UK: 6
EN: 7
RU: 5
AI status
Completed
Completed
100%
Causes
- Damaged or corroded pedal sensor connector or pins
- Broken wiring, chafing, or intermittent short to ground/power on track 2 conductor
- Faulty pedal position sensor (potentiometer track 2 internal failure)
- Poor ground or 5 V reference supply from ECU
- Contaminated or seized pedal assembly affecting sensor movement
- Faulty ECU input or internal short (less common)
Symptoms
- Reduced engine power / limp-home mode
- Check engine light (MIL) illuminated
- Delayed or erratic throttle response
- Pedal position and engine response do not match
- Possible stored related codes for throttle/pedal correlation
What to check
- Read and record stored DTCs and freeze-frame data with a diagnostic scanner
- Visually inspect pedal connector, wiring harness, and nearby harness clamps for damage or corrosion
- Check for loose or damaged pins at the pedal connector and ECU connector
- Verify 5 V reference and ground at the pedal connector with IGN on (see signal_params)
- Backprobe signal wire while operating pedal to observe voltage behavior
- Perform wiggle test on harness while observing scanner or multimeter for intermittent faults
Signal parameters
- Reference supply (Vref) at pedal connector: approximately 4.75–5.25 V (IGN ON)
- Signal voltage (track 2) with pedal at rest: typically around 0.5–1.0 V (manufacturer-dependent)
- Signal voltage (track 2) at full pedal travel: typically around 4.0–4.5 V
- Signal should vary smoothly and monotonically with pedal travel (no jumps/dropouts)
- Resistance between sensor tracks and ground: varies by design — consult OEM spec if available
- Shorts: signal ≈ Vref indicates short to 5 V; signal ≈ 0 V indicates short to ground or open circuit
Diagnostic algorithm
- Connect a capable scan tool and note DF975 / P2120 plus any additional codes and freeze frame data.
- Clear codes, perform key ON / engine OFF test to see if code returns and to capture live data.
- Visually inspect pedal connector and harness for damage, corrosion, or water ingress. Repair as needed.
- Backprobe pedal connector: with ignition ON measure Vref (should be ~5 V) and ground continuity to ECU ground.
- Measure track 2 signal voltage at rest and while slowly depressing pedal. Confirm smooth change between ~0.5 V and ~4.5 V.
- If signal is stuck, intermittent, or out of range, perform continuity and resistance checks between pedal connector and ECU pin to detect opens/shorts.
- Perform wiggle test on harness and connectors while monitoring signal or live data to reproduce intermittent faults.
- If wiring and connector tests are good but signal is faulty, replace or bench-test the pedal assembly per manufacturer procedure.
- If a new pedal still shows wrong signals, investigate ECU supply, reference, and input circuit; consider ECU repair/replacement only after wiring and sensor are confirmed good.
- After repairs, clear codes and perform road test and live-data check to ensure proper operation and that DF975/P2120 does not return.
Likely causes
- Loose/corroded connector at the pedal or harness
- Wire broken at a flex point (near pedal or firewall)
- Failed potentiometer inside the pedal assembly
- Intermittent open/short in track 2 wiring
- Low or missing 5 V reference or bad ECU ground
Fault status
Status
DF975 -> P2120: Pedal potentiometer circuit track 2 fault. ECU detected an open, short or implausible signal on the pedal position sensor track 2 input. Check pedal connector, wiring, reference voltage and sensor operation.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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