Hi all,  My fabia 2003 mk1 1.2 54htp is showing a fault code p0172 bank 1 running rich yet it has just passed its Mot. Is this a common fault I have searched everywhere for possible causes as to why im getting this code i clear it and it returns within a few days I would of assumed that if it was running rich it would have failed the emissions test at the time of the mot as i was having this code before it had the Mot done 

It could be an intermittent problem that wasn’t apparent during the MOT, hence the pass. 

 

 

 

The fault code was present at the time of the test i was just about to clear the code when the guy came over to take the car on to the test ramp so didnt get time to clear it thats why im scratching my head as to what it could be 

Then the emissions had to be within tolerance during the MOT and NO engine management light on the dash otherwise it would have failed. 

Hi jars thats what is so puzzling I expected it to fail the emissions. I just cant work out why im getting p0172 car drives ok no warning lights even when the fault code is present. If i didnt have the obd reader i would have never have known the fault was there its definitely a head scratcher lol 

When were the plugs last changed / when was the last full service?

Edited 4 April, 20215 yr by jars

Hi jars I fully serviced the car 3 months ago oil , oil filter new plugs air filter fuel filter and coolant change 

I’d start with moving either the plug to another position (after deleting the code) and see if moves with it. 

Sorry if this is a dumb question but all the plugs are bank 1 so would i still not see p0172 rich code even if i moved a plug from says cyl 1 to cyl 2

Bank 1 means cylinder number one. If the issue is with the plug and you move it to cylinder 2 the code will move with it and show as bank 2. 

7 hours ago, jars said:

Bank 1 means cylinder number one. If the issue is with the plug and you move it to cylinder 2 the code will move with it and show as bank 2. 

 

No, boxer and vee engines have 2 banks of cylinders, inline engines only have one.

You're barking up the wrong tree.

Excessive richness is more likely due to a faulty ECT sensor or pre-cat Lambda probe.

Hi all i got my hands on a laptop with vcds-lite fully registered and a Gendan (i think thats the make) cable for the fabia so im going to have a look tomorrow as to what could be my issue with po172. Any pointers in the right direction as to what i should look at would be a great help

19 hours ago, pebo48 said:

The fault code was present at the time of the test i was just about to clear the code when the guy came over to take the car on to the test ramp so didnt get time to clear it thats why im scratching my head as to what it could be 

 

The warning light may have been obscured within the instrument cluster,  

If the car was first used before 1st July 2003 it is not required to work for MOT. See end of spark ignition section: 8. Nuisance - MOT inspection manual: cars and passenger vehicles - Guidance - GOV.UK (www.gov.uk)

 

See if it comes on briefly when ignition is turned on.

 

 

Check that engine coolant temperature as reported through VCDS is consistent with ambient temperature when the engine is cold and gets to around 90C when fully warmed up.

 

There's always the possibility that the emissions test machine was out of calibration during your test, What were the numbers on your print-out?

Edited 5 April, 20215 yr by Wino

Hi Wino,

The EML comes on briefly when the ignition is turned on  so I know its working and not a duff bulb,  the car was first registered sept 2003 so EML would be part of MOT.

Can you tell me what measuring blocks I need to look at to check coolant  temperature, I`m new to vcds so still reading up on how to use it as for my emissions print out 

I have uploaded a picture of it.

 

 

 

  

I guess the fault isn't happening often enough to put the fault light on then.

CO is higher than it ought to be on the fast idle test, so something's not quite right. Does the car do mainly short trips?

One of the fields in engine module measuring block 001 is coolant temp, I think?

Is it an AWY code or BMD code engine? (Will be found on boot floor build sticker).

 

Yeah Wino mostly just around town rarely on motorway, tanks for the tip on measuring blocks will hook vcds up later this morning and see what I find 

the engine is an AWY has a full service history up to  2017  I only got the car november just gone 

Check for vacuum leaks. Brake servo vac pipe and the pipe coming from PCV valve. If you're not sure where I mean, stick up a photo of your engine bay and I'll annotate it for you.

Great Wino will put a pic up later I did look for vacuum leaks along the brake servo pipe it looks quite new but will look again as for pvc valve I have no idea what or where that is  lol

Ok hooked up vcds and took a few pics ECT was bang on with outside temp at start up. I took a few pics of other blocks still trying to work out what they mean

Engine at operating temp and reading from vcds

Since operating temperature is about 90 degrees then, as I suspected the ECT sensor is duff.

"B1S1 Not OK" is a bit of a giveaway, I think.

 

That's the pre-cat oxygen sensor not healthy (or just sooted up excessively?).  Are there any fault codes other than the one in the title when you scan the engine module?

 

Did you take it for decent drive (10-minute plus) before the 'operating temperature' screenshot?, seems like it hasn't got fully up to temperature, judging by the needle and the number? (Or the sensor is out of spec.)

 

Italian tune-up may be advisable and then look again.

Edited 5 April, 20215 yr by Wino