I have a bit of a long tale on this one so please bear with me and i will try to make it as easy as posible.

Its an astra 1.4 petrol our customer bought a week or so before it came in with EML on.

We found code for 02 sensor b1 s1 and also pipe between MAF and intake split.

The firm who he bought the car from payed for a new pipe and we fitted it and reset the light/codes.

A week later it came in with light on again , i left the codes in and scoped the sensor. It had no activity but after clearing the code it worked fine??

Back in a week later with no activity at all again ,same code this time sensor had good earth,and battery voltage correct, heater wire ok but no signal. Flat lining at about .075v

Fitted new NTK sensor and all was good, .2-.8 signal. Happy customer.(one strange thing i noticed was the plug was full of engine oil so i cleaned it out)

2 weeks later and its back in, same code.

New sensor appears to be dead??? The last sensor i took off looked new too, why is it so??

If the wiring or ecu was at fault wouldnt it still give a signal? I have 4 wires. One earth,one 12v with ignition on and 14 with engine running. A heater wire and signal wire with 0.075 output engine running at 2000rpm warm.

Could this be caused by overfuelling as i tried to rich the mix by spraying some brake cleaner down intake, this had no affect apart from causing the engine to die a bit. scoped Maf to find its a little rough but seems to do as expected. On solus it says no1 lean mix .01 ish and no2 rich .6v ish

i have took note of code but forgot to bring it home. I was not heater related or open circuit.

My boss believes it could be a faulty sensor but i dont think so as the original sensor looked like new.? I think fitting a new one will only be a short term fix.

any thoughts or help would be great.

What are your fuel trims?

What is your MAF doing?

Regards
Carl

maf reading 1 volt at idle i believe and sharp jab on throttle gives 4.5 at highest point.

2000rpm stft 0% i cant remember the others but none were scary within + or - 5% ltft

thanks for help.

>>> .(one strange thing i noticed was the plug was full of engine oil so i cleaned it out)<<<

Is it back and if so where has it come from?

Look at live data and see what changes when the fault code is cleared.

Did it have the words "adaption limit reached/execceded" or something similar?

Mark

Mark, i will get code info i wrote down today and let you know the p code. And yes there was some more oil in the plug this time too. It has also been cleaned and i have took the plastic outers of the plug now as i believe the only way it can get there is by an oil top up missing the hole.??
thanks, regards brad

You may want to think about capillary action.

Mark

I have thought of that too espetially with the plug appearing to refill.?

I have the codes now,
p0130 o2 sensor circuit b1 s1 low voltage.

p0130 o2 sensor circuit b1 s1 range/performance.

I think this is the first time the low voltage code has appeared. I just noticed my aprentice has written the same p codes for both so one isnt correct p code.

Its back in tommorrow i think so i may tweek open the back of the ecu to see if its full of oil. The only place i can think of it coming from is the pressure sensor is there anywhere else it could be from??

regards Brad

Cut open the old sensor and see if there is any oil inside it.

Mark

good idea, will do

Common fault this guys.

The oil pressure switch leaks & forces oil into the harness, which terminates at the O2 sensors.

New sensors & oil pressure switch required & some imaginative thinking about how to prevent the remaining oil in the harness from ruining further sensors.

I usually pop the orange rubber seal out of the multiplug so that the oil can seep away.

Plus warn your customer that you can not guarantee the sensors, as they are not designed to withstand oil contamination.

The official repair would require a replacement engine harness I suspect.

Thanks Dave and Mark,
I have never heard of this one before but did experience what you mean.

The plug on the ecu had oil in the bottom half,along with the oil switch plug and also a bit was back in the 02 sensor plug.
I removed the ecu and found it to be full of gel so the oil cannot get in.

Replaced the oil pressure switch and 02 sensor and told customer of the problem and asked them to return friday so we can check the 02 sensor plug again.(i think i will remove the seal in the plug as you suggested Dave)

thanks again Brad

Warning.

If there is oil inside the connector plug be very careful what you clean it with, Lambda sensors don't like oil as you have found out.

But you need to know most cleaners will affect the sensor in the same way.

Think about how they work and it will become clear how any chemical can upset the operation of the sensor.

Mark

Thanks Mark,
I used brake cleaner and the blow gun on the airline to clean the plug then a little switch cleaner but i didnt need to clean thelabda side of it as it got a brand new labda anyway.
It was back in yesterday after a few days of running and plug is still dry and completely free of oil so i believe its sorted now.
Thank for the help regards Brad.