1.8t P0172 System to rich

PieMan1

RMS Regular
Messages
319
Morning All,

Just got an Octavia vrs 1.8t and funny enough the engine light popped on last night ( shocker )

Plugin the code reader and its P0172 System Too Rich which comes up with quite the list of issues it could be, car runs fine with the code, maybe slightly less power.

Is there anything this could be? I'm a TDI guy at heart so a bit lost when it comes to a 1.8t. I know it's hard to diagnose via the internet so not expecting miracles lol.

Car is running a stage 1 map and that is it.
 

PieMan1

RMS Regular
Messages
319
vacuum leak would have been first guess but you say its idling/running fine? if it only occurs on boost then might just be a loose jubliee clip somewhere allowing leak when under pressure.
I'd hope it is as thats easy fixed. I don't think its a boost leak as it would be serious down on power?

tough one over the internet to diagnose. its going to a mechanic next week for T/Belt etc so will hopefully get it sorted then.

The joy of cheap second hand cars lol.
 

cormac81

RMS Regular
Messages
7,428
Location
Lurgan/ish
Drives
GTI, VRS, Superb
vacuum leak would have been first guess but you say its idling/running fine? if it only occurs on boost then might just be a loose jubliee clip somewhere allowing leak when under pressure.
Yeap the vacuum pipes at the front are notorious. Check for splits.
 

Gambit

RMS Regular
Messages
12,210
Location
where the sun always rises
yes but it might not be a generic vacuum line. for example mine was caused by this pipe - which isn't an off the shelf item as each end is different diameter

 

PieMan1

RMS Regular
Messages
319
yes but it might not be a generic vacuum line. for example mine was caused by this pipe - which isn't an off the shelf item as each end is different diameter

Appreciate the help dude. Cars going in on the 4th so will say to the mechanic if he can do a leak test? I take it this would pick up any issues?

Again thanks :grinning:
 

purplea4T

RMS Regular
Messages
2,810
Location
Bangor
Usually the vacuum leaks bring up a lean running fault instead of the rich running. The 1.8ts are notorious for killing vacuum and pcv lines though.
Its also another problem buying a remapped car - has the fuel pressure regulator been changed to a 4 bar one or is it the standard 3 bar?
 

PieMan1

RMS Regular
Messages
319
Yeah I've been reading up on it. Will be replacing the vacuum lines ASAP.

Again your point above is true , I wouldn't be sure if it has been changed. It's mapped by autotune so I'd assume its all been accounted for .
 

PieMan1

RMS Regular
Messages
319
I'll get a look when I'm home and see if i can see if anything is obviously off ,

Great introduction into 1.8t ownership lol.
 

vw1500

RMS Regular
Messages
352
Location
Belshaft
Drives
VW
Mine threw the light on a couple of years ago, 1st time in 4years, hose perished, then mechanic noticed another couple were ready to go. Just down to age. I got all genuine ones and weren't that dear.
 

PieMan1

RMS Regular
Messages
319
Mine threw the light on a couple of years ago, 1st time in 4years, hose perished, then mechanic noticed another couple were ready to go. Just down to age. I got all genuine ones and weren't that dear.
Yeah its the way it goes with older cars & countless metres of vac hose lol.
 

purplea4T

RMS Regular
Messages
2,810
Location
Bangor
I'll get a look when I'm home and see if i can see if anything is obviously off ,

Great introduction into 1.8t ownership lol.
As Jim says, the pcv hoses and vac lines have been in there for 15 plus years, they get cooked by the turbo heat soak and carbon from the oil, its always a thing on 18ts to sort, ive had at least 7 over the past 10 years and have had to change the hoses on every one.
On the plus side, theres so many guides for replacing them or indeed doing away with the pcv system, carbon canister, secondary air pump, all the stuff that does give problems on them.
Thermostats are a service item, coolant temperature sensors aren't much better, coils pop but are easy changed and nothing is a fortune to change.
I've a feeling yours will be down to something stupid, whether it be a airflow meter, dying plug or coil or o2 sensor - something ignition-y.
As i said before, usually pcv leaks give a lean running fault due to the extra unmetered air.
Temp guage sitting bang on the middle of the guage? Drop when driving? Any smell of oil fumes after a run whilst idling? Any damp patches around the pressure regulator or injectors?
 

PieMan1

RMS Regular
Messages
319
Gets to what I estimate a 70degrees , goes to 90 if heats off. No oil smells or fumes after 10 seconds of start up ( condensate) no dampness around the injectors.

Hose off the end of the inlet is perished but that's all I can see
 

vw1500

RMS Regular
Messages
352
Location
Belshaft
Drives
VW
That's a very comprehensive response! As said that needle should go to 90 pretty quickly and stay there, this happened mine on my way home after buying it in middle of winter, was a cold 50mile journey home lol
 

PieMan1

RMS Regular
Messages
319
Does it sit bang on 90 when driving normally with heat on?
Any oil smell after the car has been running for a while, ie nice and hot?
No drops back to 70 once heat is on .

No not really. Nothing out of the ordinary. The bay looks pretty dry.
That's a very comprehensive response! As said that needle should go to 90 pretty quickly and stay there, this happened mine on my way home after buying it in middle of winter, was a cold 50mile journey home lol
It does get to 90 but fluctuates.

I do apologies boys yous are trying to diagnose via the Internet with an absolute noob. Virtual pints are owed 😅😅😅
 

purplea4T

RMS Regular
Messages
2,810
Location
Bangor
No drops back to 70 once heat is on .

No not really. Nothing out of the ordinary. The bay looks pretty dry.

It does get to 90 but fluctuates.

I do apologies boys yous are trying to diagnose via the Internet with an absolute noob. Virtual pints are owed 😅😅😅
First port of call is to change the thermostat and temperature sesnsor. The car is over fuelling due to it defaulting back to a cold start map and throwing fuel through, hence the rich running and fault code.
 
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