Hi, today my Polo failed it's MOT on the lambda reading. The test sheet says it needs to be between 0.97 and 1.03, and the reading was 1.13.
The mechanic said that the CO2 was "all over the place" too, but the emissions passed all other tests.
He's going to have a look at it tomorrow for me, but has anyone got any ideas what the cause could be and how much I could expect to lay out to get it sorted?
He confirmed that the Cat is working ok, which is a good job as it's only 6 months old!
I've read about the throttle body needing cleaning on these Polos, but the mechanic said that a clogged up throttle body is unlikely to cause the emissions problems, and that if I clean the throttle body out it will make my idle worse.
I really appreciate any help or advice anyone can offer me!
Thanks
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need all the other readings to be able to judge, but if its only the lambda then iether there is a small air leak in the exhaust or his gas analyzer has a small air leak picking up oxygen where it shouldn't be.
If the Co was all over the place then it would of failed on the Co as well
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Thanks for your response, I've got the rest of the readings here:
Fast Idle Test
CO Level @ 2597 rpm - 0.19% PASS
HC Level @ 2597 rpm - 15 ppm PASS
Lambda @ 2597 rpm - 1.13 FAIL
Second Fast Idle Test
CO Level @ 2714 rpm - 0.19% PASS
HC Level @ 2714 rpm - 12 ppm PASS
Lambda @ 2714 rpm - 1.13 FAIL
Natural Idle Test
CO Level @852 rpm - 0.11% PASS
Thanks for your help
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Hi , That would suggest an air leak in the rear exhaust box or the testers sample hose. Ring the station back & find out if they have experienced more failing on Lambda.
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The car is back at the garage today, so will get in touch with them shortly and I'll let you know what they find.
Thanks for your suggestions
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Finally got it back! Turns out it was the lambda sensor. He said "it was knackered, and the wire connecting to it was all green and corroded". I thought the sensor was a bit steep at £65+VAT, but glad it's sorted now.
Thanks again for your help.
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Glad its sorted but |i smell a rat.Normally if the sensor is faulty the co will be drifting high & the HC's will be high as well. lambda is too much oxygen, cause by an air leak in the exhaust or sample hose of the test equipment.
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