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Discussion Starter #1
Hi,

156 2.0 JTS (2003) I have recently experienced a 'Motor Control System Failure'. This time, I have been advised by a dealer, the fault code indicates cat efficiency out of limits or low. This however, apparently can be down poor Lambda sensor connections or the CAT. i.e. the pre and post CAT figures do not match. Anyway to save some money on the basis that it may not be the CAT, I purchaded an elm 327. Next time the fault came up I managed to also determine the same i.e. CAT efficiency. I was also able to interogate the sensor readings which shows only one lambda (out of four) giving a voltage. This clearly isnt' correct as they should all be giving around 400mv I believe.

Does anyone have any thoughts. Suggestion would be that the Lambda's are not working however surely this would throw up a Lambda fault code. Also the two pre cat sensors (5 wire, wide band - very expensive) have been replaced about 5000 miles ago.

Any help would be great.
 

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I expect (as your dealer hinted at before you purchased the scanner) that it is a poor connection to the Lambda sensors.
It was a common issue with the 2.0JTS when it first came out.
 

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Discussion Starter #3
Hi thanks for the reply. Agree this could be the case as the dealer at the time tied back the sensor wire's - to stop them moving about as much. However the sensors are already hard wired, which I understood was the fix for the known problem you mention. Will check wiring over the weekend. Thanks
 
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