Seems like this is not an uncommon code to get. Just wondering, since this has popped up twice in the last 2 weeks, what the solution is. Is it better to replace the O2 sensor (front one, right?), or get the simulator? Any help is appreciated.

 

A simulator will not "fix" the problem, so you'll see less than optimal power and fuel maps because the computer isn't reading and responding.

Are you on 91 or 93 octane, race gas? For as tuned as you are this could just be a a timing adjusting issue.

Where do you get gas? Bad gas could be the culprit, a few tanks of gas from a busier Top Tier gas company might clean out the system.

This isn't the typical O2 sensor failure code, check for leaks, with the amount of mods done to the exhaust, a bolt may have worked its way loose, or similar for the air to be getting out and messing up what he sensor is expecting.

O2 sensors on the MINI are known to get dirty and throw codes, may need to pull it hit it with carb and choke cleaner and just put it back in.

Then after checking those points I'd go O2 sensors then cat Cat as being the source of your troubles. If it is the Cat a simulator might be a cost effective temporary solution however it may continue to get worse, which depending on your area's emission standards could be troublesome legally.

 

I can get mine to turn on like clockwork, since my own P0420 code gets thown only during a specific type of driving... under 3k RPM for a long period of time.

i.e. 6th gear on the freeway at 2600-ish RPM is the usual condition that throws this code.

My car has less then 6k on it, and it only started happening once I had the cam, header, and pulley installed.

It doesn't suprise me much, nor does it bother me to see the Check Engine light come on...

I'm thinking it's due to the single cat on the header, vs. two cats on the stock manifold... especially since the code states that 02 sensors are too similar in readings, throwing the code.

http://www.obd-codes.com/p0420

Of course, if your setup is stock, it's possible you have other issues...

 

No, I'm nowhere near stock. I'll check for leaks and inspect the sensor, see what's up. Nobody's using the simulator?

 

You can just buy a CEL eliminator for the 2nd o2 sensor and that will solve your problem. It extends the position of your 02 sensor and turns the check engine light off. I had the same problem and it fixed it right away. You will just need a tool to reset the light. You can find them for around $20.

This is what I am talking about.

http://www.amazon.com/Check-Engine-L.../dp/B000LI5W2W

 

p0420 is catalyst efficiency low, meaning your cat is going bad. you either have a bad cat or an aftermarket/racing cat installed. any leaks in the exhaust or intake will throw a lean/rich code. to fix the problem you will need to replace the converter.

or you can just get rid of the code. to fix the code you can install an O2 sensor simulator for the secondary O2 sensor, which is what i did. you will not see any performance decrease whatsoever as the engine computer uses the primary O2 for fuel mixture readings. the secondary O2 only monitors the cat.

 

I'm about to install a decat downpipe on my R56 and was wondering if anyone has had any success with an O2 simulator?

o2simulator.com lists one for 02-06 Mini's.

 

if the cats going bad there is no way to cheat it by doing the o2 sensor simulator right ? I would assume not, just wanted to make sure

 

[QUOTE=tow hook;4486757]if the cats going bad there is no way to cheat it by doing the o2 sensor simulator right ? I would assume not, just wanted to make sure[/QUOTE

works fine on R53, can't speak for newer engines. i've had no converter with a simulator on mine for about 10 years.

 

at what mileage did your code come on? and what brand of cat did you get ? mine has 108k on it. thx

 

my stock cat didn't fail, i replaced the stock header with an aftermarket header with a race cat on it. the internals of the race cat got loose and plugged up the cat so i had to gut it. this was about 10 years ago give or take a couple years. so i don't have a cat at all on it. i use an O2 simulator that cycles between -0.3 volts and 0.3 volts, i don't remember the brand or where i got it. it was about $40 or less.

 

ok thanks for the info, we ordered a stock replacement down pipe. and we ll see how long we keep it. I do love the car , its just the amount of money I've put in to it in 4 years that we have owned it has been kinda sad.

 

https://www.pelicanparts.com/More_In...FSO2CAT90S.htm

O2 sensor spacers / defoulers that have a built-in microCAT. Generic alternative available for approximately $45 on eBay.

This will remove the rear O2 spacer - the one telling someone their cat / lack-of-cat has gone bad - as well as filter the exhaust stream a bit more. Seems these have good reviews within the Porsche community for preventing cat-related CEL when running high flows or test pipes.