P0171 Pontiac -

Question

On a Aztec would the upstream of sensor be bad if I was throwing a code of pe 11 it's running to lean

Answer 1

HI there,

There can be a few causes for a lean condition, the upstream O2 sensor on bank 1 is one of them. Also, you will want to check and make sure you don't have any vacuum leaks. A vacuum leak at the intake manifold will also cause a lean fuel mixture condition.