Undoing a tune - do I need a new ECM?

[npmd]

Hello everyone,

I live in Massachusetts and purchased an LR4 from out-of-state that unbeknownst to me arrived with a tune. It failed emissions because the catalyst monitor is unsupported. It other otherwise drives great but I will need to undo the tune and turn on the catalyst monitor to pass emissions in MA.

My mechanic thinks it will need a new ECM and the dealer thinks either the existing ECM or an alternate used ECM can be reprogrammed. I've also read about owners rolling back the tune for emissions and then reapplying it, which I might be interested in depending on how it drives without the tune.

As far as I'm aware, the tune is software based in the ECM and there aren't any aftermarket parts like supercharge pulleys installed.

Can the existing ECM be reprogrammed back to stock?

If that is possible, how difficult is it to apply / roll-back a tune as needed for emissions testing, etc?

 

[powershift]

It depends on your smog rules. In CA if the ECM is modified with a tune then it will never pass even after reverting to a stock tune.

 

[npmd]

Thank you. So the existing ECM could be reprogrammed back to stock, correct?

I will ask my emissions contact if it can pass in MA with a reprogrammed ECM.

 

[Jimmy Brooks]

I’m not an expert on this but if you have a factory ECM you should be able to reflash it. If it’s an aftermarket clone then you’ll probably need to replace it. I don’t believe these ECMs are locked like modern day BMWs and other brands so it should be the factory one and you should be able to reflash.