Code
P1664
FIAT
P — Powertrain
Throttle angle repeat signal above maximum value
AI status
Completed
Completed
100%
Causes
- Faulty throttle position sensor (TPS) or accelerator pedal position sensor
- Short circuit to battery voltage (B+) in sensor signal wiring
- Open or high-resistance ground or reference circuit
- Corroded/loose connector or poor pin contact at sensor or ECU
- Faulty wiring harness (chafing, damaged insulation)
- ECU input circuit fault or internal calibration error
Symptoms
- Illuminated Check Engine Light (CEL)/MIL
- Reduced engine power / limp-home mode possible
- Erratic or unresponsive throttle response
- Sudden high or unrealistic throttle position readings in live data
- Possible engine stall or inability to accelerate smoothly
What to check
- Read freeze frame and live data with a diagnostic scanner; note throttle angle and related sensor voltages
- Verify whether code is current or historical and attempt to reproduce condition under same operating state
- Visually inspect throttle body, pedal sensor, wiring harness and connectors for damage, corrosion, or pin displacement
- Check battery and chassis ground connections for cleanliness and tightness
- Back-probe sensor connector and measure signal voltage, reference (usually ~5 V) and ground with key ON (engine off)
- Wiggle wiring and connectors while monitoring live data to detect intermittent faults
Signal parameters
- Typical reference voltage: ~5.0 V (varies by manufacturer)
- Expected sensor output range: approximately 0.5–4.5 V (idle to WOT)
- Tolerance: sensors commonly within ±0.1–0.2 V of expected values
- A reading above about 4.8–5.0 V is generally considered above maximum and will trigger an over-range fault (exact threshold varies)
- Two-sensor systems should show proportional outputs and proper correlation
Diagnostic algorithm
- Connect a capable scan tool and record live data for throttle angle, accelerator pedal sensors, reference voltage and ground. Clear the code and attempt to reproduce.
- Visually inspect sensor and ECU connectors for corrosion, bent pins or water ingress. Repair or clean as needed.
- With ignition ON (engine OFF), back-probe the sensor connector: verify reference voltage (~5 V), ground continuity to chassis/ECU ground, and measure signal voltage. Note any voltage >4.8 V.
- If signal is high, disconnect the sensor and re-check wiring voltage at the harness side. If high persists with sensor disconnected, suspect short to B+ or ECU fault.
- Perform a continuity/resistance check from sensor signal and reference wires to the ECU pin to find opens/shorts. Repair damaged wiring.
- Wiggle-test harness and connectors while monitoring live data to find intermittent faults.
- If wiring and connectors are good but sensor output remains incorrect, replace the TPS/accelerator pedal sensor and retest.
- If new sensor still shows over-range, consider ECU input circuit fault; consult manufacturer service info, check for software updates, and consider ECU repair/replacement as last resort.
- Safety note: take precautions to avoid unintended throttle movement while testing. Do not operate vehicle with unsecured connectors or open wiring harnesses.
Likely causes
- Short to B+ on TPS/sensor signal or reference wire
- Faulty throttle position or accelerator pedal sensor
- Poor connector contact (corrosion, bent pins) at sensor or ECU
- Damaged wiring harness between sensor and ECU
Fault status
Status
Throttle position/angle signal is above permitted maximum range — over-voltage or out-of-range input detected.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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