Gibby860

iTrader: (15)

Last acouple months I have had CELs and cleared DTC's. Today ago another CEL and thru EVOscan I read the code.

P0420 - Catalyst system Efficiency below the Threshold (Bank 1)

What is my RA telling me? Bryan from GST?

I'm presently custom AMS Flash with boost pill, however switched up GST 91 V2 to see if I have any CEL with the cold weather coming.

evil03

iTrader: (2)

sound like you will need to space out the rear o2 sensor.. or have gst delete it form the tune?

Tommy Di Cat

iTrader: (2)

^^ +2 had it happen on my turbo Galant.

Gibby860

iTrader: (15)

I only started to get CEL when temperature started to drop and get damp out. I'll see if I get with GST V2.

Evil03, what do u mean "need to space out the rear o2 sensor"? The UR Cat has the same position for the O2 senor as factory Cat.

evil03

iTrader: (2)

urmm if your tuned you shouldnt have this problem...


but any how

here is how to fix that problem i am stacked 3 deep (1) HELP! 42009 (2) HELP! 42002 HELP! last one is drilled out 1/2 to fit the o2 sensor.. 12k no problem

Kieffer87

iTrader: (2)

I've got the same code with the UR test pipe, even with their bung. I purchased a 90 degree bend O2 spacer that is popular with the VW guys. Hopefully I can get this installed soon and get rid of that pesky CEL.

evil03

iTrader: (2)

(1) HELP! 42009 (2) HELP! 42002 HELP! is the cheapest way to do the fix

Piper747

iTrader: (2)

You can disable the rear 02 by setting Options 2 bit 1 => "0".
You will probably get a p 139/140 after that.
I have the xml for that code posted in this thread for 53600010.
This has worked for my test pipe.

Westbound&down

anyone with an aftermarket dp/test pipe will probably get the code.

Essentially its telling you the cat is not efficient and is allowing pollutants into the atmosphere.

Nothing to worry about. I got tired of clearing it months ago.

Gibby860

iTrader: (15)

Haven't got another code, but I was away and cleared it. I re flashed my ECU with GST 91 V2 and all seems well. I been running UR HF Cat since June/July and only got the code acouple times. But I noticed the turbo cutting in and out under hard acceleration since the re-flashed.

Gibby860

iTrader: (15)

Got the same code again and cleared it tonight.