How do you reset computer on 2003 Tahoe after replacing knock sensor?

There's no "reset" button for the computer in a 2003 Tahoe after replacing a knock sensor (or any other sensor, for that matter). The PCM (Powertrain Control Module) learns and adapts to the vehicle's conditions over time. After replacing the knock sensor, the PCM needs to re-learn the optimal engine timing and fuel delivery based on the new sensor input. This happens automatically through driving.

There's no special procedure required. Simply:

1. Ensure the knock sensor is correctly installed: Double-check the wiring and connection. A faulty installation will lead to ongoing issues.

2. Start the vehicle: Let it run for a while, ideally at least 20-30 minutes, varying engine speeds (but avoiding excessive revving). This allows the PCM to gather data from the new sensor.

3. Drive the vehicle: Drive the Tahoe for a significant distance (at least 50-100 miles) under varying driving conditions. This is crucial for the PCM to fully re-learn and adapt.

If the check engine light remains illuminated after this, you should have the codes scanned using an OBD-II scanner to identify any remaining issues. The problem might not have been solely the knock sensor, or there might be a problem with the new sensor's installation or the sensor itself.

In short: There's no "reset." Just drive it. The computer will re-learn on its own.