986 with 200 cell cats. Low cat efficiency - Page 2 - Boxster/Cayman - PistonHeads UK

Since having 200 cell cats fitted to my facelift 986 Boxster S I occasionally get the the check light come on which is always banks 1 & 2 low cat efficiency. This usually occurs when cruising under light throttle loads. I know it is a result of fitting the 200 cell cats and it is not really problem but more of an annoyance however is there a way stopping it happening other than the obvious thrash it everywhere or go back to standard cats? Can it be coded out somehow? I would appreciate advice Thank you

Use right angled lambda spacers on the rear lambdas.

edc said: Use right angled lambda spacers on the rear lambdas. Thank you for that. Could you explain how that works please. Cheers

It spaces the lambda out so that the gas flow it sees is within the parameters. As you've seen he car performs the same whether the CEL is on or not for the rear lambda. I've had mine on a Dyno with the exhaust gas analyser and the AFR is fine.

Thank you for the info. I will get some on order.

These will be going on as soon as I shake off this horrid cold.

That’s useful to know. I have the same very occasional issue with my 996 C4 3.6 since the 200 cell X-pipe cats went on. I’ve been keeping a record of the dates and fault codes returned and it can be months and months between it happening.

No good with 90degree ones. Not matter how I tried just did not have the space or wire length to fit. Many scraped knuckles later I have decided to try some small straight spacers to see if they do the trick! Hopefully next weekend providing they are here in time.

I used the straight ones previously and they didn't work. After a few ignition cycles the CEL came back. The code was always the same and initially I cleared it with a basic OBD tool but in the end didn't bother. I blew a hole in those sports cats a few years ago and went straight to the 90 Deg ones on some new sports cats.

Mmmm Maybe I need to look at extending the leads then. With the standard ones they are just not long enough no matter how I orientate the 90deg elbow. Can you buy lead extenders or will be cut and splice time?

I used the one from Profusion so once tightened the angle can be adjusted.

I like the idea but it wouldn’t matter which direction I pointed them the lead would not be long enough so still need to extend somehow.

I bought a pair of the Profusion 90deg spacers and after a lot of manipulation got them installed. The wires are quite tight on the one side so I may extend as I have the leads off an old pair. Only installed last weekend so not many miles as of yet but so far so good and no cel light. Thank you for advice and recommendations.

Bright Halo said: I bought a pair of the Profusion 90deg spacers and after a lot of manipulation got them installed. The wires are quite tight on the one side so I may extend as I have the leads off an old pair. Only installed last weekend so not many miles as of yet but so far so good and no cel light. Thank you for advice and recommendations. Hi Halo. Same issue on my car. Did these do the job? Cheers!

flatsix.ant said: Bright Halo said: I bought a pair of the Profusion 90deg spacers and after a lot of manipulation got them installed. The wires are quite tight on the one side so I may extend as I have the leads off an old pair. Only installed last weekend so not many miles as of yet but so far so good and no cel light. Thank you for advice and recommendations. Hi Halo. Same issue on my car. Did these do the job? Cheers! Hi Yes so far but only covered about 200 miles so far, hopefully get some more on it this weekend.

I've had them for several years with no CEL.

If all else fails, these or similar mini cats get good reviews : http://brondex.com/mini-cat-o2-sensor-cel-fix/mini...

I’ve put a couple of hundred miles on it now and all seems well, no cel light. Prior to fitting the spacers it would have definitely lit up by now. Thank’s for the help and advice. I’m still a bit concerned by the length of the wire and it being stretched at some point, need to splice the extension in.

Another 200 odd miles and no light Reckon I can call that sorted!

For those interested a bit of a post script to this. Although I put on a couple of thousand miles including a track day at Anglesey I was still bothered by the sensor wires being tight due to the 90degree bend in the lambda sensor spacer. I changed them for 45 degree spacers which gave loads of slack to the sensor wires. Unfortunately this also resulted in the emissions light coming on! Who would have thought that the difference between the 45 and 90 would result in the warning light? The ultimate solution which I have now done is to switch back to the 90 degree spacers and extend the sensor wires using some old sensors to ensure there is plenty of slack. So far after a couple of hundred miles all good. Edited by Bright Halo on Tuesday 4th July 22:13

Sometimes it is worthwhile trying two straight spacers instead of one.

CEL back on after having back box changed as it was corroded and leaking. Replaced with a top gear item that is quite loud but sounds nice especially at high revs. Not sure why changing the back box would cause a CEL? I know I could just put up with clearing the code every 100miles or so but I wanted it gone so after much faffing and experimenting I have now added a straight extension to the 90degree spacer which allows me to go back to standard length wires. Maybe just maybe the soldered joints were resulting in more resistance causing the border line CEL? Approx 400miles and no CEL. Hopefully gone for good!