2011 XC60 T6 Evap P0172 Code

xyourobob · Post by **xyourobob** » 19 Jul 2025, 14:55

We have been dealing with a pesky leak in the Evap system, eventually we broke down and took it to the dealer. They determined it was the gas cap, go figure, I bought 2 off Amazon and they both leaked? They had a used cap laying around and put it on for us, no charge other than the evaluation fee. 2 weeks later the light has come back on with a P0172. I have Vida and a high end OB2 reader, both tell me the Evap leak test fails. I checked the gas cap while the car was running, it was tight, when I took it off to check the seal the car immediately starting choking and acting like it was going to stall, I'm hoping that symptom might prompt one of you gurus to narrow it down for me.

Vova585 · Post by **Vova585** » 19 Jul 2025, 21:20

Sorry for your troubles, but i doubt we can be of much help here without proper diagnostic tools. I would advice you to never buy any car parts from Amazon or ebay(unless used oem or from reputable dealer website like tasca autoparts). Better buy parts from fcp euro(not a sponsor of mvs), ipd usa(stick to oem parts and avoid their in house rubber components) or dealer.
On the other hand P0172 is "fuel system too rich bank 1". Why do you think it is evap code? Yes it is possible that purge valve is broken and stuck open and you are getting extra fuel vapors inside the engine, but it can also be due to oxygen sensor(s), maf, vacuum leak, faulty fuel pressure sensor, faulty fuel injector....I would advice to send back to the dealer and pay for 1 hour diag fee and figure it out. You can offcourse try to play with your scan tool and figure out if your purge valve is stuck open vs appropriately works(command it to close and try to blow into it), can close purge and vent valves and monitor if the pressure inside the tank raises vs staying close to atmospheric indicating leak in evap system, look at your fuel trims....

xyourobob · Post by **xyourobob** » 20 Jul 2025, 08:45

Thanks Vova, I will look to make the appointment in the morning.

It's a new purge valve on there.

My scanner said "Evap test failed"
Yesterday, after taking the gas cap off with the engine running resulted in the engine sounding like it was going to stall.

This morning I started her up and sprayed carburetor cleaner around the hose connections, purge valve, air cleaner & oil trap to see if I could identify the location of the leak, no success with doing this. I did pop off the gas cap and the engine didn't change at all, unlike yesterday.

I put the scanner on her and these are the results:

Vova585 · Post by **Vova585** » 20 Jul 2025, 13:27

Hard to say anything at this time. It looks like car is in control since achieved closed loop. However -21% long fuel trims are of concern. Leaky fuel injector? Faulty o2 sensors? Purge valve not fully closed despite being new(same argument as with other parts, where you got it from? ) restricted catalytic converter?
You can clean the MAF with proper fluid. Make sure nothing is stuck inside of the sensor. Recheck purge valve to assure it is fully closed. You likely have lots of fuel in your oil at this time which further makes your trims run negative.

xyourobob · Post by **xyourobob** » 21 Jul 2025, 17:38

Called Volvo, they told us 8/16 is the soonest they can get us in for a check engine light (almost a month out) they said as long as the light isn't blinking it's safe to drive, I'm not convinced of that, and it's my daughter's car, I'm not going to risk leaving her stranded out there, I'm going to follow your advise from your prior message, should I be able to use Vida to narrow this down?

Vova585 · Post by **Vova585** » 21 Jul 2025, 20:16

If you are planning to keep this car long term- invest in vida. Currently your code is "system too rich bank 1". Path of least resistance until you are waiting for appointment. Check air filter and make sure it is clean and not totally plugged(doubt you would get it to that point, but just in case), remove Maf and clean with maf cleaner fluid, inspect for debris at maf contact wire. Inspect if no cracks in intake pipe between maf and throttle body. Can change spark plugs(if it is time to do them it would be not a waste of money). Can change the oil with valvoline restore option(may help clean engine and possibly vvt screens). If you have time and tools can remove injectors and inspect if they are leaking(doubt, you woukd be complaining of hard start, long cranking time after car stays overnight so fuel pressure dropps to 0psi. ). But sure can swap injectors from 1-2-3(bank 1) to 4-5-6(erase the code and drive, if the code migrated to bank 2 you have faulty injector(s),. Question, why the purge valve is new? What happened there and where you got that part from? Remove purge valve and try to blow through it. If any air passes throught-defective valve.
Do not worry about evap monitors at this time. After you erase codes, evap and catalytic might take long time to "pass" usually at least 3 drive cycles.
Of course it could be a failing Upstream O2 sensors, but those are expensive and I would wait to call it without much investigation. Not sure if volvo uses identical 02 sensors for bank 1 and bank 2 upstream. If yes, you can swap them and same logic applies as with injector swap-if code moved to bank 2-faulty sensor.
Hope helps a little. Good luck.

Post by **Krons** » 21 Jul 2025, 20:38

On gas caps I’ve had success on the aftermarket ones swapping just the o-ring, leaving the OEM cap in place. It works if o-ring is same design and dimensions.

xyourobob · Post by **xyourobob** » 11 Aug 2025, 15:24

A couple of weeks ago I replaced the spark plugs, I replaced the two O rings on each injector, I cleaned the MAF and I changed the oil. Unfortunately it still threw the same P0172 code and I had to put it on pause due travel plans. I ordered a replacement Purge Valve before I left and I just installed it and she is no longer throwing the code. Thank you Vova585, I replaced the purge valve when I was dealing with another code that was fixed with a Volvo gas cap replacement. I bought that purge valve from one of the auto parts chains and I should have suspected something was amiss because the rubber mounting sleeve had a different size hole then the original so I zip tied it to stay in place. It's all good, I took care of some much needed maintenance. Thanks to everyone who chimed in.