Mechanics

P0420 CODE

2003 Pontiac Vibe

Engine Mechanical problem
2003 Pontiac Vibe 4 cyl Two Wheel Drive Manual 220000 miles

hey, guys I replaced the trans. Bearings, took car for a ride, the engine light came on, I pulled the code p0420 cat. Eff. Below threshold bank 1.I took the cat. Out and it was clean could see light through.I removed code, comes back at the same time every time, 40min. Of driving on hiway, I wil replace 02 sensors next, any ideas thanks
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Toy-8844
April 4, 2009.



O2 sensors would be the logical assumption, if CAT is not clogged.

Mmprince4000
Apr 5, 2009.
Replaced both 02 sensors, works great, bought both for 60.00 $ canadian from global-automotive from ebay brand name is Delphi, thanks guys for the tip

Tiny
Toy-8844
Apr 11, 2009.
Great news !

Mmprince4000
Apr 12, 2009.
I have this same error code, I have 120,000 KM and the Cat is warranted until 130000km or 8 years

Should I take it the the dealer, or replace both o2 sensors first just like you did?

Tiny
Kamloops
Apr 23, 2009.
Replacing the O2 sensors is a logical step, but also check the CAT like previous poster.

Mmprince4000
Apr 24, 2009.
Its a 2003 but the cat is still under warrenty. I just dont want to take it to the dealer and then they tell me no its not the Cat and then charge for o2 sensors that I could replace myself.

Tiny
Kamloops
Apr 24, 2009.
The dealer will normally check the CAT by doing a backpressure test, where they remove one of the O2 sensors and install a fitting to a gauge to test for excessive backpressure.

If CAT is not bad, you are under no obligation to have them replace the O2 sensors, just tell them you want a backpressure test performed, get results and go from there. You will, of course, have to pay for test.

OR, remove CAT yourself (it's bolted on) and inspect for black soot, melting, cracking.

Handle CAT carefully, DO NOT DROP IT.

Mmprince4000
Apr 24, 2009.