P0124 Throttle Position Sensor/Switch "A" Circuit Intermittent

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P0124 Throttle Position Sensor/Switch "A" Circuit Intermittent

What Does Code P0124 Mean?

Diagnostic Trouble Code P0124 indicates that the Engine Control Module (ECM/PCM) has detected an intermittent or unstable signal from the Throttle Position Sensor (TPS) "A" circuit. The TPS voltage may momentarily drop out or spike due to a faulty sensor, loose connector, damaged wiring, or poor terminal contact, causing inaccurate throttle position information.

Symptoms

  • Check Engine Light (MIL) illuminated
  • Intermittent hesitation during acceleration
  • Reduced engine power (Limp Mode)
  • Engine surging
  • Rough idle
  • Poor throttle response
  • Occasional engine stalling

Possible Causes

  • Faulty Throttle Position Sensor (TPS)
  • Loose or corroded TPS connector
  • Intermittent open or short in the wiring harness
  • Poor terminal contact
  • Damaged electronic throttle body
  • Excessive vibration affecting the wiring
  • ECM failure (rare)

Typical Circuit

ECM (5V Reference)
        │
        ├────────────► TPS Sensor A
        │
Ground ─┘
        │
Signal ─────────────► ECM

Signal Flow

Accelerator Pedal
        │
        ▼
Throttle Body
        │
TPS Sensor A
        │
Variable Voltage Signal
        ▼
ECM
        │
Throttle Control
Fuel Injection
Ignition Timing

How to Diagnose

1. Visual Inspection

  • Inspect the TPS connector for loose terminals or corrosion.
  • Check the wiring harness for rubbing, broken insulation, or heat damage.
  • Inspect the throttle body for contamination or mechanical sticking.

2. Live Data Test (Autel)

  • Open Diagnosis → Engine → Live Data.
  • Monitor Throttle Position Sensor A, Throttle Position Sensor B, and Accelerator Pedal Position (APP).
  • Slowly press and release the accelerator pedal while observing the live data.
  • Gently move the TPS connector and wiring harness.
  • If the TPS signal suddenly jumps, drops to 0%, spikes to 100%, or fluctuates without throttle movement, an intermittent circuit fault is present.

3. Multimeter Test

  • Verify the 5V reference voltage.
  • Check sensor ground continuity.
  • Measure TPS output voltage while moving the throttle and gently flexing the wiring harness.
  • Inspect connector terminal tension for loose contacts.

4. Smoke Test (If Applicable)

A smoke test is recommended only if unstable idle or lean condition codes are also present. P0124 is primarily caused by an intermittent electrical fault rather than an intake air leak.

Common Repairs

  • Replace the faulty TPS sensor.
  • Replace the electronic throttle body if the TPS is integrated.
  • Repair damaged or intermittent wiring.
  • Clean or replace corroded electrical connectors.
  • Secure the wiring harness away from heat and vibration.
  • Perform a throttle relearn procedure if required.
  • Clear the DTC and verify stable TPS readings during a road test.

Severity

High. An intermittent TPS signal can cause unpredictable throttle response, reduced engine power, and unsafe driving conditions.

Important Note

Throttle Position Sensor voltage ranges, connector pinouts, wiring colors, and throttle relearn procedures vary by manufacturer. Always consult the factory service information for the specific vehicle before diagnosing or replacing components.

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