tegwin
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| posted on 16/2/09 at 01:37 PM |
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VW Lambda probes?
My VW diagnostic program (VAG-COM) keeps comming up with errors on the Lambda probes...
So figure I should try replace them, see if it cures the problem..
Just popped into VW for prices and they are £126 each... I need two
Is this likley to be VW markup...or are they really that expensive?
Are there any decent cheaper generic ones that will be just as reliable? (or better than standard LOL)
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britishtrident
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| posted on 16/2/09 at 02:41 PM |
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Some VW probes are very expensive even from alternative sources --- I think they are wide band. ---- check with
Gendan --- http://www.gendan.co.uk/oxygen_sensors.php
However check the connections especially the heater connections first.
Lambda sensor them selves usually don't stop working with age. As they only grow slower to respond to changes in the mixture and require more
heat from the exhaust to work.
This is one reason older cars benefit from being given a blast down the road immediately before an emission test.
Before post cat lambda sensors were introduced this would have to be really bad to flag up a fault code but the downstream lambda probe has the sole
function of providing a reading to compsre with the upstream probe.
The up stream proble should always have a constantly fluctuating reading when the engine is running closed loop . The downstram sensor should give a
fairly constant reading showing a lower O2 content --- this indicates the catalyst and upstream lambda probe are working.
If durring the ECU sanity check the down stream and upstream probes when the engine should be running closed loop if the readings from the two
sensors are too similar that are too similar the ECU will flag a fault code.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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tegwin
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| posted on 16/2/09 at 02:51 PM |
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Thats quite interesting.....
Its a nightmare really because the ECU is showing intemittiant spurious readings...
But looking at the raw voltage data when the engine is running, they are behaving as expected....
I also have a similar intimittant readings outside of limit error on the ABS system..
All come and go.. So I wonder if there is some over riding electical issue... somewhere... urg.. I dont like driving around with the engine check
lights on!
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Would the last person who leaves the country please switch off the lights and close the door!
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P ?
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| posted on 16/2/09 at 03:44 PM |
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i too know how it feels when the vw needs a lil tlc.
Owning a vw corrado vr6 i remember not so long back getting the lambda probe replaced costing excess of 100quid. Try gsf car parts
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hughpinder
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| posted on 16/2/09 at 06:05 PM |
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Just been looking at the lucas guide to lambda sensors - they state that faulty lambda sensor messages are often the result of excess oxygen - e.g an
air leak in the exhaust maifold. This is especially true at MOTs where the CO NOx etc are all ok, but you have a bad lambda reading - no need to
replace the sensor - just fix the air leak!
The sensors can be damaged by antifreeze(e.g head leak), oil or excess fuel or silicone addatives in the fuel - then replace them - I would have
though that any of these would give a constantly bad signal though .
I don't know if any of these are your problem though, but I hope it helps - As stated by britishtrident I'd check all the connectors
first.
Regards
Hugh
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tegwin
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| posted on 16/2/09 at 08:05 PM |
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I have to strip a lot of the engine bay appart to do the cam-belt this weekend...
So whilst im in there, I will check the connectors etc... And have a look for leaks in the headers...
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