Impreza engine warning light keeps coming on! Any ideas?
Discussion
I have an intermittent problem on my 2004 Impreza WRX where my engine warning light keeps coming on. Has anyone expereienced a similar problem and how was it cured?
I have had the car since October 2010 and bought it with a new MOT and also purchased a 12 month 5 star AA warranty. For the first 6 months, the car ran faultlessly. In May, it failed to start shortly after returning from a 2 week holiday where the car was left sitting on the drive for 2 weeks. I managed to get it started using jump leads and never had this problem again. However, i took it to my local Subaru dealer for diagnosis and they diagnosed a faulty alternator. A new alternator and battery were fitted under warranty a week later. The car then ran without problems until the beginning of August when after accelerating out of a junction the engine warning light came on. I took it straight to the dealer (as it was on the way to where I was going) and they plugged it into the diagnostics. It registered an alternator fault but I explained that I had a new alternator fitted in May. The technician measured the voltage across the alternator and he said it seemed fine (the engine warning light also went out). The car was fine for another 2 weeks. Then last week whilst on holiday in Switzerland after driving down through Germany via the Nurburgring, the engine light came on again after stopping to refuel. We stopped for a long lunch and after lunch when I started the car, the light was off again. After stopping for fuel and restarting the light was on again. The next morning, the light was off only coming on after restarting after lunch and driving back to where we were staying. For the remaining 4 days of the holiday (including driving back all the way through France), the light never came on again.
I took the car into the local Subaru dealer for its annual service and MOT yesterday and mentioned the intermittent fault with the warning light (however it was not actually on when I took it in). I picked the car up today having spent over £1000 on the service and MOT (including a new catalytic converter) and on my way home after driving up a car park ramp, the warning light came on again. Throughout this intermittent problem, I have not noticed any drop in performance. I always use hight octane fuel and if anything, on the continent I was getting much better mpg than normal (mainly motorway driving).
Based on my experieince over 2 days in Switzerland, I would have said that the light comes on when I start the engine when it is hot but it has now come on twice whilst I have been driving. My local dealer seem generally knowledgeable and enthusiastic about the cars and I'm not having a dig at them as I have been happy with the service received at this point but they don't appear to have any ideas on what is causing this intermittent problem. I have it booked in again with them next week but am concerened that I will end up spending loads of money and not solving the problem and that when I sell or trade-in the car that it will devalue it. I am keen to get it sorted in the next month whilst the car is still under warranty. Could it be that the new alternator is faulty (although when I had the problem with the old alternator, it never triggered the warning light)?
Sorry for all the detail but I wanted to give the full context of the problem. Any ideas/advice would be very welcome.
I have had the car since October 2010 and bought it with a new MOT and also purchased a 12 month 5 star AA warranty. For the first 6 months, the car ran faultlessly. In May, it failed to start shortly after returning from a 2 week holiday where the car was left sitting on the drive for 2 weeks. I managed to get it started using jump leads and never had this problem again. However, i took it to my local Subaru dealer for diagnosis and they diagnosed a faulty alternator. A new alternator and battery were fitted under warranty a week later. The car then ran without problems until the beginning of August when after accelerating out of a junction the engine warning light came on. I took it straight to the dealer (as it was on the way to where I was going) and they plugged it into the diagnostics. It registered an alternator fault but I explained that I had a new alternator fitted in May. The technician measured the voltage across the alternator and he said it seemed fine (the engine warning light also went out). The car was fine for another 2 weeks. Then last week whilst on holiday in Switzerland after driving down through Germany via the Nurburgring, the engine light came on again after stopping to refuel. We stopped for a long lunch and after lunch when I started the car, the light was off again. After stopping for fuel and restarting the light was on again. The next morning, the light was off only coming on after restarting after lunch and driving back to where we were staying. For the remaining 4 days of the holiday (including driving back all the way through France), the light never came on again.
I took the car into the local Subaru dealer for its annual service and MOT yesterday and mentioned the intermittent fault with the warning light (however it was not actually on when I took it in). I picked the car up today having spent over £1000 on the service and MOT (including a new catalytic converter) and on my way home after driving up a car park ramp, the warning light came on again. Throughout this intermittent problem, I have not noticed any drop in performance. I always use hight octane fuel and if anything, on the continent I was getting much better mpg than normal (mainly motorway driving).
Based on my experieince over 2 days in Switzerland, I would have said that the light comes on when I start the engine when it is hot but it has now come on twice whilst I have been driving. My local dealer seem generally knowledgeable and enthusiastic about the cars and I'm not having a dig at them as I have been happy with the service received at this point but they don't appear to have any ideas on what is causing this intermittent problem. I have it booked in again with them next week but am concerened that I will end up spending loads of money and not solving the problem and that when I sell or trade-in the car that it will devalue it. I am keen to get it sorted in the next month whilst the car is still under warranty. Could it be that the new alternator is faulty (although when I had the problem with the old alternator, it never triggered the warning light)?
Sorry for all the detail but I wanted to give the full context of the problem. Any ideas/advice would be very welcome.
No specific advice on that model but cars record fault codes every time the light is triggered so it does NOT matter if the light is on when it goes into the dealer, they can see what's being going wrong anyway.
Obviously we need to know the fault code - if it's still reporting a fault relating to the Alternator I'd suggest that something else was either damaged by the old alternator or was the actual cause of the fault which caused them to replace it (e.g. there was nothing wrong with the old Alternator!!)
This is where a good autospark comes in - dealers tend to just read fault codes and replace parts but a good autospark knows that electricals are always more complex and that problems in one area can trigger fault codes in another.
A faulty alternator would be pretty obvious anyway - basically your battery goes flat and/or the red 'charging' light will flicker-on, rather than the orange Engine Warning/Stop Light.
When you had it serviced did they not mention what the fault codes were? They should have checked them, they may even have cleared them but if it's come on since, the codes will be there, waiting to be read and if they have no idea, it's time to find a good autospark (I can recommend one in NE England!!)
Obviously we need to know the fault code - if it's still reporting a fault relating to the Alternator I'd suggest that something else was either damaged by the old alternator or was the actual cause of the fault which caused them to replace it (e.g. there was nothing wrong with the old Alternator!!)
This is where a good autospark comes in - dealers tend to just read fault codes and replace parts but a good autospark knows that electricals are always more complex and that problems in one area can trigger fault codes in another.
A faulty alternator would be pretty obvious anyway - basically your battery goes flat and/or the red 'charging' light will flicker-on, rather than the orange Engine Warning/Stop Light.
When you had it serviced did they not mention what the fault codes were? They should have checked them, they may even have cleared them but if it's come on since, the codes will be there, waiting to be read and if they have no idea, it's time to find a good autospark (I can recommend one in NE England!!)
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