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-   -   Lambda sensor problem, possible MOT fail - thoughts please (https://forum.a8parts.co.uk/showthread.php?t=14183)

HPsauce 28th May 2018 03:35 PM

Lambda sensor problem, possible MOT fail - thoughts please
 
My son's S4 again...… :o
His Engine Management Light came on a while back (not that long after a service at Audi :rolleyes: )and being unaware of the upcoming MOT changes I told him it wasn't a problem, but I'd scan it sometime.

Did that a few weeks ago, cleared the 3 errors, the light went out and so far, hasn't returned. But scanning it today 2 of the errors are there so maybe it's just a matter of time?

Initial 3 errors, cleared 3 weeks ago:
19711 - Oxygen (Lambda) Sensor B1 S1; Heating Circuit P3255 - 001 - Regulation at Upper Limit - Intermittent - MIL ON
18683 - Oxygen (Lambda) Sensor B1 S1: Negative Lead P2251 - 004 - Open Circuit - Intermittent
18675 - Oxygen (Lambda) Sensor B1 S1 P2243 - 004 - Reference Voltage Open Circuit - Intermittent
Readiness: 0000 0000
Errors found and cleared today:
19711 - Oxygen (Lambda) Sensor B1 S1; Heating Circuit P3255 - 001 - Regulation at Upper Limit - Intermittent
18675 - Oxygen (Lambda) Sensor B1 S1 P2243 - 004 - Reference Voltage Open Circuit - Intermittent
Readiness: 0000 0000

Note the 18683 error hasn't returned. We ran the car after clearing the errors and none returned so I guess they are genuinely intermittent.
My thoughts are:
1. Is the sensor failing or could it be a wiring fault?
2. What level/frequency of which error cause the MIL to come on?
3. If it does come on presumably that will now be an automatic MOT fail if not cleared before the test?
4. Could the 18683 error be a red herring related in any way to the work done by Audi on the power steering disaster in April; all completed before I did these scans?

27litres 28th May 2018 10:08 PM

Open circuit and heating failures are pretty common when O2's get a bit of age on them.
I know the steering rack is in the same general vicinity, just depends whether or not they disturb the wires getting it in or out.

For the sake of £100 in parts, it may be prudent to replace them.
Check if the plug is the same as the D2 (bit over 1" x ½" with round ends), as Bosch no longer supply the early plug as a direct replacement. I buy NTK now.


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