help needed VAG-COM errors - 1.8T VAG engine

jase555

jase555

jase555

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up north
hi folks can anybody help, engine poorly VAG codes keep coming on, basically need to know if this will be a dear one to fix. Car is 7yrs , 80k on the clock always serviced,

weird one is all of the above mpg still standard (to me anyway) results from VAG below, MOT due soon

16514 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit
P0130 - 35-10 - - - Intermittent
16514/P0130/000304 - Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit

17705 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)
P1297 - 35-00 - -
17705/P1297/004759 - Pressure Drop between Turbo and Throttle Valve (check D.V.!)

17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 35-00 - -
17544/P1136/004406 - Fuel Trim: Bank 1 (Add): System too Lean

16486 - Mass Air Flow Sensor (G70): Signal too Low
P0102 - 35-10 - - - Intermittent
Readiness: 0000 1001
16486/P0102/000258 - Mass Air Flow (MAF) (G70): Signal too Low

01314 - Engine Control Module
013 - Check DTC Memory – Intermittent

01039 - Coolant Temperature Sensor (G2)
30-10 - Open or Short to B+ - Intermittent
01039 - Engine Coolant Temperature Sensor (G2)

thanks in advance

jase
 
Reset it, drive it for a day and then post new codes.

I suspect the serious ones will stick, however I'm not convinced that all those codes mean faults / failed components.
 
All the codes relate to one common problem, however with less air getting to the engine i'd expect the fuel system to be reporting its too rich.
 
Also i'd look into getting a new G2 sensor fitted, the original black top one fail and can cause lots of running issues, the sensor itself is about £8.
 
By the looks of it you'd prolly need a new coolant sensor at least (and if you're replacing that, it may be a good idea to renew the thermostat at the same time... seeing as both parts should be cheap, and both require the coolant to be drained). The lambda sensor may be faulty, but that would need testing. As for the other three (pressure drop, fuel trim too lean, mass air flow), they could all potentially be caused by a vacuum leak.
 
MAF's are quite common to go on these engine's i've heard. Also with the Lambda it may be making it run lean or rich. This would normally be across the board though and not just one chamber...
 
I've had all of those at least once. New fuel pressure regulator sorted the fuelling being lean. The pressure drop between turbo and intake is 9 times out of 10 a loose jubilee clip on some hose/pipework. It "could" be the recirc valve as the plastic ones do tend to go, but unless its a higher powered 1.8T I wouldn't circle it out as the culprit) MAF you might as well try cleaning with carb cleaner, just a short couple of blasts to it should prove whether or not cleaning it would help.

The last two codes I'd not worry about, well I'd worry about the last one if your temperature guage isn't working properly, but other than that I'd ignore. Mine throws those two up ALL the time.
 
As above somewhere

Make a note of all codes just in case.

Reset all faults using vagcom or vcds same thing. Then see what reappears after a drive.

Some might be nothing or something.
 
Firestar_3x said:
Also i'd look into getting a new G2 sensor fitted, the original black top one fail and can cause lots of running issues, the sensor itself is about £8.
Click to expand...

hohum said:
By the looks of it you'd prolly need a new coolant sensor at least (and if you're replacing that, it may be a good idea to renew the thermostat at the same time... seeing as both parts should be cheap, and both require the coolant to be drained). The lambda sensor may be faulty, but that would need testing. As for the other three (pressure drop, fuel trim too lean, mass air flow), they could all potentially be caused by a vacuum leak.
Click to expand...

You know, I had my coolant git start beeping at me, levels were fine, and it was intermittent (notably stopped when it went to be serviced :/).
Anyway, a friend with a Mk1 Leon said had same and sorted it by scraping the contacts in the coolant tank. I did this (with a flathead screwdriver/minced beef or something) and nothing since.

When this G2 sensor 'goes' does it go completely, or intermittently as above?

Anyway yeah OP, reset and see, I understand they mount up over time.
 
It can fail in a few ways, the ECU needs a temp feed from the G2 sensor to know how warm the engine is running, i think it uses the reading to know when and how much air / fuel to inject in.

When the G2 sensor goes totally i think it leads to funny readings on the dash, the failure mode before this is an error code and bad running

Also its worth noting you have a coolant level sensor and a coolant temp sensor, both are different sensors.
 
Firestar_3x said:
It can fail in a few ways, the ECU needs a temp feed from the G2 sensor to know how warm the engine is running, i think it uses the reading to know when and how much air / fuel to inject in.

When the G2 sensor goes totally i think it leads to funny readings on the dash, the failure mode before this is an error code and bad running

Also its worth noting you have a coolant level sensor and a coolant temp sensor, both are different sensors.
Click to expand...

Hah, I just realised this as I read your post! Hopefully the level sensor was the guy with prongs sticking in the coolant. Pretty sure I recall checking the manual and reading something about level, as apposed to temp anyway.
 
Griffo said:
You know, I had my coolant git start beeping at me, levels were fine, and it was intermittent (notably stopped when it went to be serviced :/).
Anyway, a friend with a Mk1 Leon said had same and sorted it by scraping the contacts in the coolant tank. I did this (with a flathead screwdriver/minced beef or something) and nothing since.

When this G2 sensor 'goes' does it go completely, or intermittently as above?

Anyway yeah OP, reset and see, I understand they mount up over time.
Click to expand...

The level sensor is a separate beastie. I had to give my one a scrape a couple of years ago and it has been fine since.

I also had an intermittent water temperature sensor that required replacing and it is going in next week for a new lamda sensor.... all quite common problems in that fault code list unfortunately.
 
Ah yeah, my lambda (or two) went within the first week or two of ownership. It was warrantied at the time so no issue. How much do they actually cost? Some loser at a Skoda garage mentioned something in the region of 100 each (they replaced both). I thought it were mental so I just superglued a resistor with a thermometer blu-tacked to it in there instead. (Spot the lie)
 
Griffo said:
Ah yeah, my lambda (or two) went within the first week or two of ownership. It was warrantied at the time so no issue. How much do they actually cost? Some loser at a Skoda garage mentioned something in the region of 100 each (they replaced both). I thought it were mental so I just superglued a resistor with a thermometer blu-tacked to it in there instead. (Spot the lie)
Click to expand...

I got a front one from an online place and it was £86 IIRC so £100 or so from a dealer sounds about right.
 
the g2 coolant temp sensor is fairly common to go, the black ones are usually replaced with a green one (the actual colour of the plastic) so it implies some sort of revision there.
You dont need to drain all the coolant out of it to change it, just obviously make sure its not roasting hot, unscrew the header tank lid, then screw it back up again, this creates some sort of hydraulic lock in the system as stops it from squirting out every where when you remove the sensor.

The sensor is held in place with a little clip that slides in sideways, remove this clip. Pull the old sensor out, then push in new sensor with new seal (lube up seal before hand, makes it go in a lot easier) Then push in the sensor while pushing the clip around / over it. Then obviously connect the plug to it.

The coolant level sensor is in the header tank, usually you would replace the whole header tank as it has the sensor built in, not very expensive i think around £20-30.

The fuel trim is probably from a block breather system, you will probably want to take the throttle body off and give it a clean with some intake cleaner, getting rid of all the oil and gunk. Also clean the breather pipes to it.

the Intermittent faults you dont really need to be worrying about too much, but the coolant one is very common. They can cause all sorts of faults + running problems. As sugested replace this sensor, delete all the memory fault entrys then try it again in a week. See if the static faults are clearing.

hope this helps a little
 
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