Should the voltage fluctuate for both O2s or will HO2S1 fluctuate and HO2S2 stay steady?

Question

2010 Chevrolet Colorado 2.8L, on a scanner should the voltage fluctuate for both O2s, or will HO2S1 fluctuate and HO2S2 stay steady? I have the engine code P0420

Answer 1

Sensor 1 will typically fluctuate very fast, sensor 2 should create a slow fluctuation normally from .3 volts up to or close to 1.0v If both sensors act the same when the converter is good and warmed up, then the converter is not doing anything. If you see the slow movement on the rear O2, then the sensor is fine and the converter is no good.

Comments

Sorry milonajo1, if the rear o2 sensor is fine and shows slow movement, that catalyst is fine, if the rear o2 sensor fluctuates badly then the cat is no good..

Answer 2

P0420 CHEVROLET - Catalyst System Low Efficiency Bank 1

Read more: https://www.autocodes.com/p0420_chevrolet.html