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EGT Again

Discussion in 'A4/S4 forum(B5 Chassis)' started by dublinS4, Jul 2, 2013.

  1. dublinS4
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    dublinS4 Member

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    Hi. I keep getting the 2 egt sensor codes 17865 Exhaust gas temperature sensor 2 open/short to B+. When i clear the fault and drive for another mile or so i get these 17866 Exhaust gas temperature sensor 2 short to ground and 17863 Exhaust gas temperature sensor 1 range/performance. My questions are.... What side is egt sensor 2 on? If sensor 2 is faulty will it make sensor 1 faulty(show up fault code)? I have heard of a quick fix by splicing the two sensor to one(using the good sensor).. The car seems a little slower and alot thirstier but is not going to full limp mode.. Its a 98 s4
    Cheers
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  2. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    the "range/performance" code MIGHT be caused by something else (ie a faulty maf or lambda) or it might be a duff sensor.

    The open/short is definitely a duff sensor.

    I suspect that given you think its only a little slower with EGT faults, there is other issues going on. Craigs S4 was MASSIVELY slower when EGT fault appeared.

    I think your best bet is just to buy and fit two new EGT sensors. They're cheaper when you buy the set, so you'll only end up costing yourself money buying 1 first then buying the other when you realise its also faulty. Might be worth looking at the MAF and lambdas too once you get the EGT's fixed.
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  3. dublinS4
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    dublinS4 Member

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    Thanks for the reply. Wouldnt any other faults show up as codes when i do a scan?
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    no, sometimes sensors can become faulty and give erroenous readings, but that are within the acceptable range. This typically confuses the ECU.

    Say for instance, your engine flows 300grams of air, and the maf says it only flowed 200, the ECU will just accept 200 as correct, and the fuelling will then be incorrect. The ECU might then notice the fuelling is incorrect, and think the lambda is faulty, so you get a fault code for the lambda, when infact its working fine.
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