Question

2008 Chevrolet Avalanche 5.3L Flex, could a weak alternator cause this code? when I use accessories like power windows the headlights

Answer 1

HI there

This should not happen with a weak alternator. This is a code for the throttle position sensor and in most cases cleaning the throttle body can eliminate the code. If not then the tps must be replaced.

Answer 2

P0121 CHEVROLET - Throttle Position Sensor 1 Performance
Read more: https://www.autocodes.com/p0121_chevrolet.html