One-time P0420
#1
Senior Member
Certified GM nut
Thread Starter
One-time P0420
Cam install, one week later: while driving in the rain today, I got a check engine light while cruising gently uphill: P0420 set, another P0420 pending. I cleared the codes to see if they would return, and they didn't. The code means that I either have a massive exhaust leak, my rear O2 sensors are showing too little change, or my cat is dying.
(Less than a month before my emissions test, and I get my very first emissions-related CEL. It figures.)
Here'* what I've looked at and what I plan to do:
Anything else I should check out?
(Less than a month before my emissions test, and I get my very first emissions-related CEL. It figures.)
Here'* what I've looked at and what I plan to do:
- I've noticed no loss of top speed or power, so I'm guessing my cat is fine. Last time I gave it a good knocking (during the cam install), nothing rattled.
- I reused the exhaust pipe gasket when reinstalling the engine, because it was in good shape and not flattened. I'll replace that the next chance I get.
- I checked the fuel trims and the voltages of the O2 sensors at idle and while cruising (25-35 mph), but that was pointless, seeing as how I don't know how to interpret the data.
Anything else I should check out?
#2
DINOSAURUS BOOSTUS
Expert Gearhead
Sure..first thing is list the code description.
Ok, I'll do it, but keep in mind it'* your responsibility.
Catalyst below efficiency. This means the difference between the reading on the front and rear O2'* doesn't have enough of a difference. Aka your whacking could have broken up the honeycomb and screwed up your cat.
Stop on over and that code will .... no longer be a problem
ps..bring money to take me to dinner.
Ok, I'll do it, but keep in mind it'* your responsibility.
Catalyst below efficiency. This means the difference between the reading on the front and rear O2'* doesn't have enough of a difference. Aka your whacking could have broken up the honeycomb and screwed up your cat.
Stop on over and that code will .... no longer be a problem
ps..bring money to take me to dinner.
#3
Senior Member
Certified GM nut
Thread Starter
By "a good knocking," I meant a few taps with my bare knuckles. If that'* enough to do it, find some Kryptonite.
Grabbed my scanner and went out to the highway last night. Did a couple WOT pulls while watching the intake manifold pressure, which fluctuated as it normally should. That rules out a blockage. I'm going to follow the GM eSI P0420 troubleshooting today to see if the cat is flowing but dead.
So, if the code comes back, I'll pay you a dinner visit.
Grabbed my scanner and went out to the highway last night. Did a couple WOT pulls while watching the intake manifold pressure, which fluctuated as it normally should. That rules out a blockage. I'm going to follow the GM eSI P0420 troubleshooting today to see if the cat is flowing but dead.
So, if the code comes back, I'll pay you a dinner visit.
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