Hi all,
I have an Astra 1.4 i (1998, last week the Engine management light came on while driving (drove fine apart from light). Now when starting the car it has a very high idle speed and the engine mangement light comes on after a count of 5. I analysed the ecu 'blink codes' and it came out as 21 which I believe is a problem with the throttle position sensor. I tried disconnecting the sensor but still very high idle speed.
Can anyone give me a pointer as to what I can try next?
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If the ECU light is on, it means the engine goes into "get you home, or to a garage" mode. Don't continue to drive the car for too long before fixing, as depending on the fault, you could fro instance be using more fuel, which in turn could damage the Cat.
First thing I would try is resetting the ECU by disconnecting the battery for a couple of mins. Make sure you have the radio code to hand though.
I did have a link to a Vauxhall ECU code site, but can't find it at the moment to check Code 21. If I find it, I'll report back.
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I did have a link to a Vauxhall ECU code site,
Found it: www.knighta.f9.co.uk/info/fault_codes/fault_codes....m
Code 21:-
Item: Throttle Potentiometer Sensor (TPS)
Fault: High voltage
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Thanks for the quick reply Dave,
I have already tried disconnecting the battery, but the problem persists, any other ideas?
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If its a potentiometer with the wiring plug pulled off, should three pins be revealed check for continuity of resistance between the three i would expect a reading between all three pins, if not it may be faulty. (not sure if these are pots having never had one fail)
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Fluff,
Quite a common problem, and often it is a faulty sensor. Checking resistances is Ok so far as it goes, but really you need to look at the output voltage, on the central pin, with the connector in place and the ingition on. The reading should rise and fall progressively with throttle movement, but a digital voltmeter may not be quick enough to catch glitches. The only 100% accuarte way is to view it on an oscilloscope, and you are looking for a momentary break-up in signal, or "hash", ususally quite low down in the range as this is where most movement takes place. Sensors not That expensive, around £30 from Webcon.
Regards, Adam
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Are they carbon track pots, Adam? One of the worst inventions known to electronics, after the electrolytic capacitor, especially in the under-bonnet environment.
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Have never opened one up, but you can be fairly certain that this is indeed the case.
Adam
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Purchased a new Throttle Position sensor, fitted it and everything is fine now - idle speed back to normal and no engine management light.
Thanks to everyone that replied, this is a great resource
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