P0124
Throttle Position Sensor/Switch A Circuit Intermittent
Powertrain Speed/Idle Control Throttle Position Sensor 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

Your throttle position sensor is sending inconsistent signals to the engine computer, like a light switch that flickers on and off. The ECU can't reliably determine how far open the throttle is, which disrupts engine control.

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Symptoms You May Notice
3 known symptoms for this code
Engine hesitation or surging during acceleration
Check Engine Light illuminated intermittently
Rough idle or stalling at stops
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECM monitors the throttle position sensor (TPS) voltage output, which should change smoothly as you press the accelerator. The sensor voltage must stay within expected ranges and change consistently; intermittent faults occur when the signal drops out, spikes, or becomes erratic.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
TPS Voltage 0.5–4.5V (smooth progression) Voltage drops below 0.2V or above 4.8V, or signal intermittently disconnects
Voltage Rate of Change Proportional to throttle movement Abrupt jumps, sudden drops, or missing signal frames detected
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
TPS connector and wiring harness
Inspect the connector for corrosion, loose pins, or damaged wires; reseat the connector firmly or clean contacts with electronics cleaner.
2
Throttle body and TPS assembly
Remove the throttle body, clean carbon buildup around the sensor, and inspect the TPS for physical damage or contamination.
3
Throttle Position Sensor (TPS)
Replace the TPS unit if connector and wiring are sound; note that some sensors require calibration or relearning after installation.