Hi all you helpful people,

Had the Eml light on and off for 2 years now. Never bothered me. Car runs fine and get average of 43mpg over urban and B roads. However looking to move the car on and understand that it will be a big No No for people so looking to get it sorted. The initial Eml light came on for the EGR valve. I bunged some cleaner through and seemed to of cleared it. It then came back on 18 months ago and the 2 times I've had the code read and cleared it is

 

17598 - Linear o2 sensor reference voltage implausible p1190 - intermittent 

 

I've checked the pre-cat sensor coming out of the manifold and no obvious burnt/disconnected wires and unplugged the cable to check it is connected properly as read that possible to put 4 pins in wrong way round. Mine has 6 pins and definitely no way to plug it in wrong. 

 

Can anyone offer up any advice as to what issue could be and next steps/cheapest checks first before I replace the sensor. 

 

Thanks in advance

Sorry should say model is 1.4 16v sport

The official instructions for dealing with that fault code (and three other associated ones) suggest checking ignition components as well as the lambda sensor itself, so I think I would have a look at the spark plugs, as well as maybe a look at the tip of the sensor to see if it looks excessively sooty or anything.

 

– Testing lambda probe and lambda control upstream

of catalytic converter ⇒ Chapter 24-4

– Testing lambda probe heater upstream of catalytic

converter ⇒ Chapter 24-4

– Test ignition leads and spark plugs ⇒ Chapter 28-1

– Test combustion misfiring ⇒ Chapter 28-1

 

44 minutes ago, Wino said:

The official instructions for dealing with that fault code (and three other associated ones) suggest checking ignition components as well as the lambda sensor itself, so I think I would have a look at the spark plugs, as well as maybe a look at the tip of the sensor to see if it looks excessively sooty or anything.

 

– Testing lambda probe and lambda control upstream

of catalytic converter ⇒ Chapter 24-4

– Testing lambda probe heater upstream of catalytic

converter ⇒ Chapter 24-4

– Test ignition leads and spark plugs ⇒ Chapter 28-1

– Test combustion misfiring ⇒ Chapter 28-1

 

Thank you, what/where are the chapters you are quoting and any suggestions on how to clean the tip if excessively sooty.

Those are other parts of the pdf document. They mostly refer to connecting up various VAG-specific bits of test equipment, so are probably not going to be much use to you.

I just thought it worth passing on that it could be an ignition-related problem, as well as a problem with the sensor itself.

 

I've heard of people cleaning up contaminated lambda sensors with a blowtorch. Never tried it myself though.  It was more an idea to see if it looked as if it might be in poor condition, prior to spending cash on a replacement. Because it's in such a hot location, it probably will look relatively clean unless the engine is consuming oil? 

 

Oh, while you had the 6-way connection apart, did you eyeball the wiring coming off the mating half?

Edited 22 July, 20187 yr by Wino

1 hour ago, Wino said:

Those are other parts of the pdf document. They mostly refer to connecting up various VAG-specific bits of test equipment, so are probably not going to be much use to you.

I just thought it worth passing on that it could be an ignition-related problem, as well as a problem with the sensor itself.

 

I've heard of people cleaning up contaminated lambda sensors with a blowtorch. Never tried it myself though.  It was more an idea to see if it looked as if it might be in poor condition, prior to spending cash on a replacement. Because it's in such a hot location, it probably will look relatively clean unless the engine is consuming oil? 

 

Oh, while you had the 6-way connection apart, did you eyeball the wiring coming off the mating half?

Ok, thanks. Yep on the other half of the plug the wires coming out looked fine. I'll check the plugs and sensor and I'll go from there.