This code just won't go away on my car. Last came on 2 months ago to the exact day and about 2000 miles ago.

I reset it with my obd reader and it will be on again in the next few thousand miles.

The freeze frame data seems to indicate the fault occurs at 50% throttle at about 60mph (2800 rpm)

MAP sensor shows 98kPa which IIRC has been consistent both this time and when I had the fault 2 months ago 

I initially thought the upstream lambda sensor may have been causing the problem however using the graph on the obd reader seems to indicate a decent sensor output of what you would expect

 

Anyone have any suggestions before I stick some tape over the light to stop it annoying me!

What does the line on the graph do?

Sensor 1 (which I assume is the manifold one) shows a trace which goes up and down when idling and then increases in frequency after the revs are raised and settled. As the revs are building or dropping the graph trace shows no signals.

Ive not had a chance to check it as Im driving to see what happens under load.

It almost seems like because the fault occurs under cruise conditions that its when the engine is running stoichiometric and is at its hottest.

I do check for pending codes regularly and nothing was showing previous to this.

I should also say it tends to happen on longer journeys >1 hour at higher speeds

 

I doubt I'll get a chance to do any log runs tomorrow to try to recreate those freeze frame conditions to see what my (MAP/other) data looks like, I'm off abroad for a week on Sunday morning. Happy to do so when I'm back though.

My experience of sensor 1 (the manifold one) output is that within a very short time (30 secs) of start-up from cold it settles into a steady voltage, as it's a wideband sensor causing dynamic correction of fuelling. So it doesn't just alternate either side of stoic, but instead the ECU uses its output to 'hold' stoic rather than flip about either side.

How much does the voltage on yours vary by when it's alternating?

 

I've got logs of her AZQ I can dig out.

Look at the wideband lambda, it may have drifted out of spec. causing the over-leaning flag to be set.

The voltage on idle seems to go between 0.785 and 0.05 i think

My main suspect was always the lambda sensor but then when I checked the graph it all seemed ok.

I suspect being 10 years old and 106000 miles that its getting on a bit.

Can't justify spending the £35 for a new sensor at the moment especially if its not that causing the problem.

Its not affecting performance or economy that I can notice so will probably stick to resetting the light when it comes on.

6 minutes ago, clarendon462 said:

The voltage on idle seems to go between 0.785 and 0.05 i think

My main suspect was always the lambda sensor but then when I checked the graph it all seemed ok.

I suspect being 10 years old and 106000 miles that its getting on a bit.

Can't justify spending the £35 for a new sensor at the moment especially if its not that causing the problem.

Its not affecting performance or economy that I can notice so will probably stick to resetting the light when it comes on.

 

£35 is an unbelievable price for a wideband, mine just cost twice that and that was half the price of a genuine one.

Your right, I was looking at the rear ones.

Fronts are £57 aftermarket

Any point trying a used one off a newer car or am I wasting my time

 

(I think i already know the answer)

Edited 14 April, 20179 yr by clarendon462

Hmm, looking at this, the BME may have gone back to a narrow band precat sensor. That's only a four-pin connection, I think?

Surely not, it must just be a common earth for the heating element and the sensor. Everything is wideband these days.

His voltage readings suggest narrowband too.

I thought wideband ones always had 5 or more connections. 

 

Edited 14 April, 20179 yr by Wino

Most of them are five, mine is, I just can't believe that engine can meet Euro 4 without a wideband sensor.

 

Edit: What voltage readings? I see no voltage readings.

Edited 14 April, 20179 yr by sepulchrave

Surprising to me too.

 

If it's narrowband then it will certainly need replacing at this age and mileage.

Current flow diagrams show same 4-pin schematic symbol for pre- and post-cat sensors for BME, I think confirming a narrowband sensor in both locations.

What behaviour is the post-cat sensor showing?

Edited 15 April, 20179 yr by Wino

must be narrow band as the listings on ebay show the wideband sensors for AZQ engines

It is only 4 pins on the connector same as the post cat sensor

The post cat sensor voltages are much closer together, can't remember exactly will need to go out and check but the voltage is around 0.485 IIRC and fairly stable at that

 

Edit: http://www.ebay.co.uk/itm/FOR-SKODA-FABIA-1-2-12V-2003-FRONT-4-WIRE-DIRECT-FIT-LAMBDA-OXYGEN-SENSOR-08508-/151567605731?hash=item234a221fe3:g:VJoAAOSwm8VUxp5d

Edited 15 April, 20179 yr by clarendon462

Good price. Pretty sure I saw another at that price that also said 2 year warranty?  Either way, worth a punt, I reckon.

Edit; looks like this one has same, now that I scroll down through the listing.

D'oh! Not to mention the banner at the top of the image!

 

Edited 15 April, 20179 yr by Wino

will be my next purchase then, I'm £70 lighter already  today having to order a new rear silencer and front pipe 

 

Hi,

I know it's been ages you had this trouble. But I'm having the same issue with my 14 years old Fabia. The fault always appears in a journey more than 1 hour driving at high speed.

Did you find out what exactly was causing this?