Code
P1224
FORD
P — Powertrain
Throttle Position Sensor B Out of Self-Test Range
AI status
Completed
Completed
100%
Causes
- Faulty throttle position sensor (TPS) B inside the throttle body
- Damaged, shorted or open wiring harness to TPS B
- Poor connector connection or corroded terminals at the TPS or PCM
- Incorrect reference voltage or bad ground to the TPS circuit
- Contaminated or mechanically binding throttle plate or linkage
- PCM fault (rare) or software needing update
Symptoms
- Check Engine MIL illuminated
- Reduced engine power or 'limp' mode
- Poor idle, surging, hesitation, or unexpected throttle response
- Possible inability to accelerate normally
- Diagnostic trouble codes related to throttle/pedal position
What to check
- Retrieve freeze frame and live data with a scan tool; note TPS A and TPS B voltages and correlation
- Visual inspection of throttle body, wiring harness and connectors for damage or corrosion
- Wiggle test of wiring while watching live TPS B signal for intermittent changes
- Check vehicle battery and charging system for stable voltage during tests
- Compare TPS B signal to TPS A across throttle range — they should correlate within manufacturer tolerance
Signal parameters
- Reference voltage (Vref) to TPS: approximately 5.0 V (Key ON, engine OFF)
- TPS B closed-throttle voltage: typically about 0.2–0.8 V (varies by model)
- TPS B wide-open-throttle voltage: typically about 4.0–4.6 V
- TPS B should change smoothly with throttle and correlate with TPS A; abrupt jumps or out-of-range values trigger the code
Diagnostic algorithm
- Read and record freeze frame data and all stored codes. Do not clear codes yet.
- Perform a visual inspection of throttle body, connectors and harness for damage, oil/contamination or corrosion.
- With a DVOM or lab scope and a backprobe, verify Vref (≈5 V) and ground at the TPS connector with key ON.
- Backprobe TPS B signal pin; slowly operate throttle (by hand or with scan tool) and observe voltage change — it should be smooth and within expected closed/WT ranges.
- Compare TPS A and TPS B live values and their correlation using a scan tool; note any mismatch or identical stuck values.
- Wiggle harness and connectors while monitoring TPS B for intermittent faults. Repair/secure any damaged wiring or connectors.
- If wiring and connectors are good but TPS B readings are out of range or non-linear, remove and inspect the throttle body assembly and sensor. Clean if carbon build-up is present and re-test.
- Replace the throttle body or TPS (as assembly) if sensor is confirmed faulty. Reconnect, clear codes, perform any required throttle body relearn / idle adaptation procedure per Ford procedure.
- If fault persists after replacement and wiring checks, consider PCM diagnosis or software update at dealer/advanced shop.
- After repairs, verify fault does not return through a full drive cycle and confirm normal throttle response.
Likely causes
- Wiring damage at harness where it flexes (heat, rubbing)
- Corroded/loose TPS connector pins
- Failed dual channel TPS inside throttle body assembly
- Carbon build-up causing throttle plate to stick and skew sensor readings
Fault status
Status
Throttle Position Sensor B out of self-test range — PCM detected TPS B signal outside expected voltage/correlation limits. May cause reduced power or limp mode.
Repair difficulty: Medium
Diagnostic time: 1.0-2.0 hours
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