P0131 Cadillac

Question

Check engine light came on & it started shaking

Answer 1

Hi there,

If the O2 sensor is not working properly it can cause a lean fuel mixture on that bank. I would start by diagnosing the O2 sensor and then clear the codes and see if the lean mixture code returns. P0171 is a lean mix code for bank 1.

P0131: 

The Powertrain Computer or PCM has determined that the Oxygen Sensor voltage remained below 400 millivolts for more than two minutes or that the Air Fuel Ratio Sensor remained in a lean-biased mode for too long .

If you have an intake manifold vacuum leak you can also get these codes.