Code
P1220
FIAT
P — Powertrain
Throttle position [signal implausible]
Views:
UK: 2
EN: 4
RU: 5
AI status
Completed
Completed
100%
Causes
- Faulty throttle position sensor (TPS) or accelerator pedal position (APP) sensor
- Open, shorted, corroded, or damaged wiring/connectors in TPS/APP circuit
- Poor ground or weak 5V reference supply to the sensors
- Contaminated or mechanically binding throttle body / throttle plate
- Failed throttle body actuator (drive-by-wire motor)
- ECM software error or internal fault
Symptoms
- Check Engine Light (MIL) illuminated
- Reduced engine power / limp-home mode
- Poor idle, stalling, hesitation or lack of throttle response
- Surging or inconsistent throttle response
- Throttle pedal position and engine throttle plate position do not match in live data
What to check
- Read and record freeze-frame and live data (TPS, APP, throttle plate angle, reference voltage, grounds)
- Compare APP and TPS correlation across pedal travel using a scan tool
- Inspect TPS/APP connectors for corrosion, bent pins, water ingress or damage
- Measure sensor reference voltage (should be approx. 5.0 V), sensor signal voltage at closed and wide open throttle, and sensor ground
- Perform wiggle test on wiring harness while monitoring live data for intermittent faults
- Check throttle body for carbon buildup or mechanical binding; visually inspect throttle plate
Signal parameters
- Reference voltage to sensors: approximately 5.0 V (nominal)
- TPS/APP signal at closed throttle: typically ~0.4–1.0 V (varies by model)
- TPS/APP signal at wide open throttle: typically ~4.0–4.5 V (varies by model)
- Two-channel sensors: both sensor signals should correlate and change smoothly with pedal/throttle movement
- No open circuit, short to battery (12 V) or short to ground; signal should be stable without rapid jumps
Diagnostic algorithm
- Retrieve all stored codes, freeze-frame, and live data with a full-function scan tool.
- Visually inspect TPS/APP and throttle body connectors for corrosion, damage or moisture; repair as needed.
- With key on engine off, measure sensor reference (≈5 V) and ground. If missing, trace and repair supply/ground.
- Backprobe the TPS/APP signal wire(s). Verify resting (closed) and full travel voltages follow expected ramp without dropouts or spikes.
- Compare APP (pedal) vs TPS (throttle) signals in live data. Look for implausible correlation or non-linear behavior.
- Wiggle the harness and connectors while monitoring live data to find intermittent wiring faults.
- Clean throttle body if binding or heavy carbon is present. Re-test after cleaning.
- If wiring and connections are good but sensor still out of range, replace the faulty TPS/APP or the throttle body assembly as applicable.
- After component replacement, perform required throttle/idle adaptations or ECU relearn procedures per manufacturer instructions.
- Clear codes and road test to confirm repair. If code returns, consider ECU diagnostic/repair or manufacturer-specific diagnostics.
Likely causes
- Damaged wiring or poor connector at the TPS or APP (most common)
- TPS or APP sensor out of specification or failing
- Contaminated or sticking throttle plate affecting sensor feedback
- Failed throttle body actuator or internal throttle assembly fault
- Loss of 5V reference or ground to sensor circuits
Fault status
Status
ECM detected implausible or inconsistent throttle position sensor signal (TPS/APP); system may limit engine power. Check sensor signals, wiring, grounds, and throttle body.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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