"He has also found that the Lambda sensor has failed along with the alternator, and the battery isn't in great shape either, so quite an expensive week. I knew the battery was starting to struggle so that wasn't a huge surprise. It is possible that the Lambda sensor failure was exacerbated by running the car with a misfire (I had no choice but to drive it home following the failure but my subsequent 'testing' when trying to find the problem may not have helped). The alternator is a part failure, it only charges at high revs and doesn't charge at low revs (<2000). Luke tells me that this is often as a result of vibration from the Duratec causing some of the windings to break." Even without dedicated test kit it's possible to get a quick look at the condition of the battery and the operation of the charging system. I usually recommend 3,000 rpm for the latter but that might have missed this one. Had you noticed any change in when the warning light came on? Thanks Jonathan