Throttle Position Sensor (DTCs Set)

1998 Chevrolet Astro Van 2WD V6-4.3L VIN WSECTION Throttle Position Sensor (DTCs Set)
The VCM calculates fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor may cause intermittent bursts of fuel from an injector. This may cause an unstable idle because the VCM detects the throttle is moving.

When the VCM detects a malfunction with the TP sensor circuits, the following DTCs will set:

^ DTC P0121 circuit performance malfunction.

^ DTC P0122 circuit low.

^ DTC P0123 circuit high.

^ DTC P1121 intermittent circuit high.

^ DTC P1122 intermittent circuit low.


For DTC testing procedures refer to Diagnostic Tables / Diagnostic Trouble Code Tables. Testing and Inspection
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.