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[Kevin Wood]

Hi Steve,

It's the post-cat Lambda sensor we're talking about moving. At the moment you have one Lambda sensor for mixture control immediately after the exhaust manifold - before any of the cats. That stays where it is.

You have a second lambda sensor for cat monitoring after a small pre-cat in the elbow of the downpipe. They you have the main catalytic converter, and then the rest of the exhaust.

The pre-cat gets tired and causes the P0430 and P0440. What we are proposing is to relocate the monitoring lamdba sensor further back behind the main catalytic converter so it is in cleaner exhaust gas even if the pre-cat is not working.

I have wondered if there's an electronic solution to the problem. It's less simple than it seems because, from what I have seen about cat monitoring systems, they do expect activity from the post-cat lambdas during some parts of their efficiency monitoring cycle. If they just saw no activity at all, they would raise a lambda sensor fault.

Kevin

[SteveMJ]

Hi Steve,

It's the post-cat Lambda sensor we're talking about moving. At the moment you have one Lambda sensor for mixture control immediately after the exhaust manifold - before any of the cats. That stays where it is.

You have a second lambda sensor for cat monitoring after a small pre-cat in the elbow of the downpipe. They you have the main catalytic converter, and then the rest of the exhaust.

The pre-cat gets tired and causes the P0430 and P0440. What we are proposing is to relocate the monitoring lamdba sensor further back behind the main catalytic converter so it is in cleaner exhaust gas even if the pre-cat is not working.

I have wondered if there's an electronic solution to the problem. It's less simple than it seems because, from what I have seen about cat monitoring systems, they do expect activity from the post-cat lambdas during some parts of their efficiency monitoring cycle. If they just saw no activity at all, they would raise a lambda sensor fault.

Kevin

Thanks for responding so quickly  That is much clearer now (I wasn't adequatley familiar enough with the topology).

So, Marks DTM said it was easy to weld a boss etc - how can this be done (and how much)?  It is not easy for me.

Steve

[Kevin Wood]

Bosses are easy enough to find. Plenty on Ebay for a fiver a go. The welding job doesn't look too bad. Could perhaps bung a local garage or welders 20 quid to do it. I'm still at the "ignoring the orange light" stage at the moment.

Kevin