Macca

There are lots of posts on the forum about the Amber engine Malfunction Indicator Light (MIL) illuminating (which is a Major Fault leading to an MOT failure). My problem is that the engine MIL light is not coming on (which is also an MOT failure, presumably as a safeguard against unscrupulous owners talking the MIL bulb out to hide a major engine fault). My 2004 MGTF Spark has been running sweet as a nut with no warnings or malfunctions on either the Dashboard or OBD and I assumed it would fly through its MOT – it failed due to the MIL Light not illuminating. When I picked the car up after the MOT, the MIL light came on for me. I dragged out the Inspector and point out his error, whereupon the MIL light would not come on during repeated ignition on – start-up events; the car remained an MOT failure. Since then, a 100% repeatable pattern has emerged. For the first start after the Alarm/Immobiliser has been deactivated, the MIL light comes on (albeit it flickers on, goes off for a quarter of a second, and then comes back solid and goes off when the engine starts (i.e. normal function). For all subsequent starts until the Alarm/Immobiliser has been cycled, the MIL light remains off. Does anyone know if this is a known behaviour or an interface issue between the Engine Management Computer and the security system? I don’t fancy my chances of telling the MOT Inspector that he has to cycle the Alarm System before he checks the MIL light operation in the re-test!