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Hello Members

I have this error below.....

P0135 Oxygen (Lambda) sensor bank 1 sensor 1: Heating circuit malfunction

which seems to be so intermitent, the o2 sensor is new, and that wiring loom 'connector block' has been cleaned and serviced many times, what do think is the next possible cause along the chain that would effect the o2 heater performance, i've done this procedure a few times cleared the error, and then 4 weeks or 3 months down the line it shows itself again.

The cars a Polo 1.4 Auto 2001, but the body shape is this mark type, i'm going to do the same procedure again today, but i know this is only a postponement of the bank 1 'O2 heater circuit malfunction' error appearing again.

So any personal, or expert knowledge would really help

Kind regards
Livio

I had the heating circuit malfunction error code as well, but my lambda sensor was screwed and so was my temp gauge, since i've swapped them both over for new ones the error code hasn't come up again.

Sorry i can't be of more help to you

Thanks h4rls, i've just now come back from using electrical cleaner, and pinching the female copper pins again to the O2 connection block, i started the car and the 'check light' didn't come on, so i cleared the fault code.

As i have mention, this isn't the first time i've done this, but at intervals of anything between 2 or 3 weeks, or it lasting 2 or 3 months.

My water temp sender has been changed in the past, just over a year ago, but i don't know if it's on the same circuit as the O2 bank 1 sensor.

So i'm wondering, is it the connector block in some way, or the wiring loom itself, or some kind of O2 relay (if anyone knows where it may be, please let me know), what i don't think it is, is the ECU.

So anymore advice would be very wellcome

I've been using the car a number of times all day today, and just whent to use it at 8 pm, started the engine, turned on the lights and a few moments later the 'check' engine light came on.

When i look at the error code tomorrow morning, i just know it will be 'Heater circuit malfunction, i'll probably do the same thing as i did today to rectify it.

Does anyone know, which coloured wire/wires on the loom side and O2 sensor bank 1 side, serve the Heater Circuit part of the sensor?

Has anyone got a clever way of tracing the cause of fault, i can tell you this is the 3rd new VW OEM sensor changed because of this reocurring reason, so i carn't believe this has failed.

Anyone with any help would be a life saver.....

regards