A quick thank-you to the forum


Oct 14, 2005
Waynesboro, VA, USA
I had my '95 FZJ in a local shop for broken exhaust brackets, oil, filter and lube and a check engine light.

The guy call me an says I need new O2 sensors and new Cats. He then proceeds to quote me around $1200 and $1100 each for the new cats. I stopped listening at this point so the numbers are ballpark.

So...Since I happened to have been perusing all the cat threads around here 'cause I'd like to get 'em turned, I asked him what the code was. P0420 he tells me. OK. I tell him I have heard a distinct whistling on acceleration, have they checked for exhaust leaks? Silence. Have they checked to see if the O2 sensors are actualy working? Well, sir the code indicates that we need to replace your catalytic coverters and O2 sensors. I asked him to just reset the code and we'd see. He told me they don't reset the code until they replace the parts, but the CEL was not on when I picked up the truck. They did say they would install parts I brought them when I told them I could get fresh cats and O2s for ALOT less than OEM.

Needless to say, some money was saved here. I know I gotta get off my fat rear and do my own work, but I can at least find a shop that will do the work I want done the way I want it done with no BS.

Thank-You All.


Staff member
Dec 13, 2002
Knee deep in hookers and gin
Given the general mark-up, they planned on making about $1500 on parts between the o2s and the cats. Replacing everything also makes the job somewhat easier for them.

The most common cause of P0420 I have seen is a loose downstream O2. It causes the rear O2 to read lean.

A bad front O2 would not cause a P0420.
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