Help.......MIL light on and causes lumpy running!!
Discussion
If it stays on and the buzzer continues to sound also, it's possibly the water temperature sensor - the electronic one, not the one for the gauge. Not too expensive just to replace on spec, but you really need the software to tell you exactly what the problem is, as it could be the air temp or some of the other sensors.
If you don't have the software [which you probably don't], then without visiting someone that does, your options would be to disconnect each sensor in turn and check the resistance. If these things fail you would often get a fully open or closed circuit, while in operation they will vary resistance depending on temperatore/pressure etc. I'd start with the water temperature as it's the one that I think is most likely to fail first, and its easy to check resistance across the terminals on a hot and cold engine.
The bumpy ride will be because the engine management system substitutes a fixed value for any sensor that fails, and when it does that the mil light comes on. If it was the temperature sensor, for example, then the engine would be given fuel for a 'hot' engine irrespective of the actual temperature.
WB
>> Edited by williamball on Thursday 23 January 13:21
If you don't have the software [which you probably don't], then without visiting someone that does, your options would be to disconnect each sensor in turn and check the resistance. If these things fail you would often get a fully open or closed circuit, while in operation they will vary resistance depending on temperatore/pressure etc. I'd start with the water temperature as it's the one that I think is most likely to fail first, and its easy to check resistance across the terminals on a hot and cold engine.
The bumpy ride will be because the engine management system substitutes a fixed value for any sensor that fails, and when it does that the mil light comes on. If it was the temperature sensor, for example, then the engine would be given fuel for a 'hot' engine irrespective of the actual temperature.
WB
>> Edited by williamball on Thursday 23 January 13:21
Does it come on immediately the engine is turned back on, or only after a while?
I would recommend taking it to your nearest specialist who's got the right software to talk to the unit, if you feel it's running OK. If you're worried about doing it damage get the AA to take you. Some independents might not have the latest software. It shouldn't take them long to diagnose the problem.
When my SP6 was new, it had a few trips back the dealer on a truck after the MIL light came on and stayed on. After about the 3rd time it was fixed - the throttle bodies weren't quite setup righ.
Sometimes still comes on intermittently, when its cold and wet. After a few minutes it's fine.
>> Edited by gilesn on Thursday 23 January 13:45
I would recommend taking it to your nearest specialist who's got the right software to talk to the unit, if you feel it's running OK. If you're worried about doing it damage get the AA to take you. Some independents might not have the latest software. It shouldn't take them long to diagnose the problem.
When my SP6 was new, it had a few trips back the dealer on a truck after the MIL light came on and stayed on. After about the 3rd time it was fixed - the throttle bodies weren't quite setup righ.
Sometimes still comes on intermittently, when its cold and wet. After a few minutes it's fine.
>> Edited by gilesn on Thursday 23 January 13:45
I'd go along with the previous diagnoses - most likely causes are water temp sensor (well known for corroding), cheap and relatively easy to replace and lambda sensor - range rover items cost about £70-£80 but are a bugger to get to. I have had them both go. Oh how I wish MBE would sell us the software but they won't so the only way you can be sure is run it to someone with the software and hook it up to the ECU.
May be I have a bad one but my 4.5 has been through 3 lambda sensors in 24000 miles.
May be I have a bad one but my 4.5 has been through 3 lambda sensors in 24000 miles.
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