Code
P0124
HUMMER
P — Powertrain
Throttle Position Sensor 1 Circuit Intermittent
AI status
Completed
Completed
100%
Causes
- Damaged or corroded TPS connector or terminals
- Broken, chafed, or intermittent wiring between TPS and ECM
- Poor or intermittent 5V reference or ground at the sensor
- Faulty throttle position sensor (internal intermittent)
- Contaminated or misaligned throttle plate causing irregular contact
- Intermittent ECM/PCM input circuit or internal fault
Symptoms
- Check Engine/Malfunction Indicator Lamp (MIL) illuminated intermittently
- Surging, hesitation, or poor throttle response
- Rough idle or occasional stalling
- Reduced power or limp-home mode if the ECU defaults
- Inconsistent throttle position PID readings on a scan tool
What to check
- Retrieve freeze frame and readiness data with a scan tool; note other stored codes.
- Verify MIL is P0124 (intermittent) and attempt to replicate the condition while monitoring live TPS PID.
- Visually inspect TPS connector, pins, and wiring for corrosion, damage, or looseness.
- Backprobe TPS signal, 5V reference, and ground; verify voltages with ignition on and as throttle is moved.
- Wiggle test wiring and connector while monitoring TPS signal for intermittent jumps.
- Check for related codes (e.g., other TPS circuits, throttle actuator faults) that could indicate shared wiring or ECM issues.
Signal parameters
- Reference voltage: nominal 5.0 V (typically within ±0.25 V) on the 5V reference lead
- Signal voltage at closed throttle: approximately 0.4–1.0 V (varies by application)
- Signal voltage at wide open throttle: approximately 4.0–4.5 V (linear increase across travel)
- Signal behavior: smooth, monotonic change with throttle movement; no sudden jumps, dropouts, or noise
- Open/short indications: signal near 0 V or >5 V, or rapid intermittent changes indicate wiring/sensor faults
Diagnostic algorithm
- Connect a professional scan tool and record P0124 freeze frame, PID data, and any concurrent codes.
- With ignition ON (engine off), backprobe the TPS connector: verify 5V reference, signal, and good ground. Compare to signal parameters.
- Slowly operate the throttle while watching the TPS signal on the scan tool or multimeter. Look for smooth, linear voltage change and note any jumps or dropouts.
- Perform a wiggle test: flex the wiring harness and connector while monitoring signal for intermittent behavior. Pay attention to areas where the harness bends.
- Inspect and, if necessary, clean the TPS connector and terminal pins. Repair or replace corroded pins; apply dielectric grease after repair.
- Check continuity between TPS terminals and ECM pins with connectors disconnected. Wiggle harness while measuring to detect intermittent opens/shorts.
- If wiring and connector are good, bench-test or replace the TPS with a known-good unit (follow vehicle-specific procedures for removal/installation and calibration if required).
- If fault persists after sensor/harness repair, inspect PCM/ECM connector and ground circuits. Consider testing or replacing PCM only after exhausting wiring, connector, and sensor checks.
- Clear codes and road-test to verify the intermittent failure is resolved and the code does not return.
Likely causes
- Loose or corroded connector pins at the TPS
- Wire harness damage where it flexes near the throttle body
- Intermittent 5V reference from the PCM due to poor ground or connector
- Degraded TPS potentiometer causing dead spots or jumpy signal
- Aftermarket electrical work or repairs that disturbed the harness
Fault status
Status
Intermittent circuit fault detected in Throttle Position Sensor 1 (TPS A) — erratic or intermittent signal to ECM.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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