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Discussion Starter #1
I recently had to have my engine rebuilt due to overheating. After I got it back, the engine light came on with an O2 sensor warning. The mechanic replaced the O2 sensor with a brand new one, but said they were still not getting any signal from it. They claim they went through the wiring harness to make sure there was not a problem with it. They say the new O2 sensor is working, but not receiving signals from the ECM and that the ECM needs to be replaced. I'm sure that's pretty expensive, and I've already got $1700 US in repairs on my poor baby.

Is there a way to "reboot" the ECM in the hopes it might reset or something? I find it difficult to believe that it has gone bad, since all the other stuff it controls still works just fine. If it is bad, do I *HAVE* to take it to a dealer? They are close to 100 miles away, and it would be an ordeal. I'm wondering if there is any way to replace the ECM myself... I have seen a few salvaged ones on ebay. But, I've read that the ECM is tied to the VIN of the vehicle and it has to be flashed with an EPROM burner to match it to the engine.

I'm still driving it, though I know that's not really great... but, it is running too lean as opposed to too rich, so I figured I'd be O.K., at least for a little while.

My Smart is a 2009 Passion. Anybody got any ideas or suggestions?

TIA!

Tom Parker
Gulfport MS - USA
 

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It is very rare for a ECM to fail unless subjected to water intrusion or electrical surge. I would start by disconnecting the battery for ten minutes and see if anything changes. If not check all the fuses. There are several fuses that provide power to the ECM and a failed fuse may affect the lambda sensor heater operation. If nothing changes get a second opinion at another shop. I would not use a aftermarket lambda sensor (O2 sensor).

Do a on-line search for automotive ECM rebuilders, such as BBA reman. They may be able to test and repair your ECM if necessary. Used units are VIN-locked and require special equipment to repair.

If at worst case the ECM requires replacement it needs to be coded and programmed with a factory original diagnostic system, which means either a dealer or properly equipped independent shop.
 

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Discussion Starter #3
Thanks so much for your advice! I will disconnect the battery and try that, then I'll check the fuses. I DID use an aftermarket O2 sensor, unfortunately. But, I still have the original one, since I believe there was never anything wrong with it in the first place.

Tom Parker
Gulfport, MS
 
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