Hello. I need to replace the lambda sensor on our Fabia, I'm wondering if anyone here has used an aftermarket one, rather than the main dealer priced one? I can't see what the difference would be in manufacturers at this point. Thanks.

Which one? There are two and they are different.

Fault code says

17604

KWP1281

That's a pre cat sensor isn't it.  Can only find post cat sensors on the usual parts places, so this may be a dealer only part!

Yes it is, "electrical fault in heating circuit" sensor 1 bank 1.

I'd be tempted to eyeball the wiring at the cable entry of the sensor itself, but more importantly the loom connector that the sensor plug connects to, down by the gearbox.

Heater wires are brown on pin 1 to engine ECU and blue/red on pin 2 from fuse 9 in the cabin, shared with the post cat sensor.

Don't buy anything before checking those; broken wires in that general area are super-common.

 

Part number of genuine sensor is 036906262G according to this page: https://skoda.7zap.com/en/cz/fabia/fab/2006-453/9/906-906000/#12 (4th from last item 12). If you click on the last box of the right side of the table, aftermarket equivalent part numbers are listed by the dozen.

Thank you. I will take a look at the wiring and the information.

Made some checks, wiring looks intact. Pins 1 and 2 measure 12v when engine is running.

 

I did try to find a pin out to check the sensor with a meter.

 

I've ordered the NGK sensor by using the list of aftermarket part numbers which was supplied in your link. I ordered mine from Cartech-One. The usual places like ECP and GSF weren't particularly helpful with this.

 

TPS wanted about £200 for one!

Do you have an open-ended 22mm spanner to get the old one out and the new one in? If it's the same as my BBY engine, there isn't room to get the normal 'split socket' on it I don't think?

Good point, I think my open ended spanners run to 19mm, after that it's offset ring spanners up to 38mm.

 

I think when I did this to my Golf, I managed to use some adjustables, but that was the one under the car, so there was more room. I should probably go and get a 22mm open ended ahead of this job.

To get the old one out just cut the lead off and use a deep socket, putting the new one in will be easy.

Don't think there's the angle for that sep, it's tucked round facing about 45 degrees back towards the engine.

A bit like this (aftermarket version) https://www.ebay.co.uk/itm/New-Genuine-BMC-Catalytic-Converter-Exhaust-BM91326H-Free-Fitting-Kit-Top-Qual/192391134880?epid=249508680&hash=item2ccb67bea0:g:6O8AAOSwc2FaKs1x:rk:5:pf:0

In that case make sure it's nice and hot before attempting removal, use a ring spanner if possible.