2009 Chevrolet HHR 2.2L engine with 76000 miles with engine code P0420

Question

2009 Chevrolet HHR 2.2L engine with 76000 miles. flex pipe broke. The dealer wanted around $225 to replace it. And most shops wanted around $170 to weld on a new pipe. I bought the whole thing on eBay. From manifold to mid-flange for $138. Put on myself. Around 20 miles later, I was hit with the P0420 code. I went to the local Auto Zone to see if my scanner was wrong. Nope P0420. Both cats are new. Anyway, possible one of the o2 sensors could cause a false read.

Answer 1

HI there

It is possible the rear O2 sensor is reading wrong. This can sometimes happen, but you also want to check for leaks in the exhaust BEFORE the converter and O2 sensor. A poorly running engine can also cause this code to appear. If there is to much raw gas going through the converter it can't clean properly and it could set this code.

Answer 2

P0420 Chevrolet Code - Catalyst System Low Efficiency Bank 1
Read more: https://www.autocodes.com/p0420_chevrolet.html