engine light

[johnemon]

2001 se 3.1 liter aprox 90,000 miles. I am getting a code 420. I have recently replaced the catalitic convertor (which was almost completly plugged) changed the plugs and wires. I have checked for vacuum leaks and found none. The code was reset several times and still comes back. Any ideas?

[BNaylor]

Originally Posted by johnemon

2001 se 3.1 liter aprox 90,000 miles. I am getting a code 420. I have recently replaced the catalitic convertor (which was almost completly plugged) changed the plugs and wires. I have checked for vacuum leaks and found none. The code was reset several times and still comes back. Any ideas?

Possibilities are the 02 sensor before the CAT and 02 sensor after the CAT. The 02 sensor after the CAT is what the PCM references to in order to generate the P0420 DTC error code. Plus there could be an exhaust leak from the exhaust manifolds to the CAT. Good luck!



Thrasher CAI, DHP v1.0 ECU,
3.25 SC pulley, CAIT GMAF, Hi-Flow CAT,
u-bend delete, 160 TS,TB spacer,
MSD 8.5mm wires, Autolite 104 spark plugs,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials

[theblurr87]

Originally Posted by bnaylor3400

Possibilities are the 02 sensor before the CAT and 02 sensor after the CAT. The 02 sensor after the CAT is what the PCM references to in order to generate the P0420 DTC error code. Plus there could be an exhaust leak from the exhaust manifolds to the CAT. Good luck!

good thing you replied. with 420 and all I thought his car might be telling him something

[BNaylor]

Originally Posted by theblurr87

good thing you replied. with 420 and all I thought his car might be telling him something

lol. With GM's programming, it was telling him take me to the dealer so they can charge you $420 for something thats DIY.

But he's fortunate its only a pending code and the car will run for days on end although the SES light would be a nag. Might lose about 1 - 2 mpg in the process.



Thrasher CAI, DHP v1.0 ECU,
3.25 SC pulley, CAIT GMAF, Hi-Flow CAT,
u-bend delete, 160 TS,TB spacer,
MSD 8.5mm wires, Autolite 104 spark plugs,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials