Troubleshooting Help: O2 Edition [updated]

"Snuze: Needs another Swede" (markg) 11/05/2020 at 09:55 • Filed to: None

0

26

The 850 started throwing a CEL and I’m trying to figure out what it means. The code is P0172, which is Too Rich on Bank 1 Sensor 1. I checked my Torque App and I can’t pull an AFR reading, only O2 sensor voltage (I think the car only has 1 sensor for O2).

My drive is 25 mph for a minute or two, to get out of my neighborhood, then about 50 mph down the parkway for a few miles, then a lot of mixed driving, multiple stoplights with distances of a few hundred feet to several miles between them, mostly doing around 30-40 mph. So lots of regular driving under normal loads.

Here are my symptoms:

Hard starting (may be unrelated)

Car seems to run and drive okay all the time

Engine comes up to temperature (according to dash gauge) in a normal amount of time (as I’m cruising down the parkway). I didn’t check the Torque App this morning.

Curiously, the heater takes forever to warm up, like the engine comes up to temp but I don’t get any heat for a while after that, but then it blows very hot.

The CEL lights up about 15 minutes after I leave, halfway into my drive. Car still runs fine. If I clear it, it stays off, until the next drive.

I’ve done some reading up on this, and the consensus among Volvo people is the P0172 is almost never an O2 sensor. But, the fact that it takes so long to throw the code even after the car is warmed up makes me wonder if the sensor heater is faulty or something. O2 sensors have a heater that is supposed to warm them up for a period of 2-3 minutes, then they should operate normally. Otherwise they take much longer to get up to operating temp. Perhaps the car is waiting for the sensor to warm up, based on expected heating of the element, and after a while it times out? Towards the end of my drive today I checked the sensor voltage on the Torque App and it appeared to be normal (I didn’t think to check it earlier).

The Volvo folks say the 2 most common culprits are a dirty MAF or a vacuum related issue. This is possible but seems unlikely to me, I serviced the Flame Trap (PCV) earlier this year and replaced a bunch of bad vacuum hoses, and had the MAF out and cleaned it. That being said, it’s still a possibility I missed a bad hose or something.

The last thing, and I just caught this randomly in a forum, is a bad Engine Coolant Temp sensor and/or thermostat. During warmup (when the O2 sensor is non functional because its still being heated), the engine adds a little extra fuel to be safe, like a choke on an old carb. It’s possible that one or both are bad, which is causing the car to always think it’s cold, thus always adding extra fuel. And if the thermostat is at fault it could also explain why the car is slow to get heat.

My plan now is to setup Torque this afternoon with a display for O2 voltage, coolant temp, and MAF readings and monitor them on the way home. Maybe I’ll even try the datalogging function, if I can figure it out. I’m off tomorrow so I should have some time to check vacuum lines and clean the MAF again.

Any other thoughts or crazy ideas?

Update: Opponaut Cmill below mentioned his XC90 did the same thing, but only on winter blend fuel. That brings up a very good point, and detail I overlooked. The last time I drove the Volvo was in early September. We have annual inspections in VA, and mine was due. It failed due to the parking brake being out of adjustment , and I didn’t have time to fix the car and get the re-inspection done before I left for a month long work trip. I did it upon my return and then had to wait 2 weeks for new tag stickers. So I just got those on and started driving the car this past Sunday. The only issue with this theory is it didn’t do this last year.  

Cash Rewards > Snuze: Needs another Swede 11/05/2020 at 10:06

0

Your extra fuel theory makes a ton of sense to me

cmill189 - sans Volvo > Snuze: Needs another Swede 11/05/2020 at 10:09

0

Sounds like you’re on the right track to me. My XC90 would throw a code for rich O2 on bank 1. It only did it on winter blend fuel.

The no heat t hough...quick and hot cabin heat is like a Volvo thing. Does it happen on every vent setting? I wonder if you have a stuck blend door.

Sovande > Snuze: Needs another Swede 11/05/2020 at 10:11

3

I’ve had this code before! It was on a 98 V70 and I finally cleared it by replacing about 95% of that vacuum hoses in the engine bay with silicone hoses (that way I knew what had been replaced) and it went away.

Here is a cut and paste that may have a few more ideas:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of “oiled” air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.

There could be a vacuum leak.

There could be a fuel pressure or delivery problem.

Possible solutions include:

Inspect all vacuum and PCV hoses, replace if necessary

Clean the MAF sensor. Consult your service manual for it’s location if you need help. I find it’s best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it’s dry before reinstalling

Inspect fuel lines for cracks, leaks, or pinches

Check the fuel pressure at the fuel rail

Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.

Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

cmill189 - sans Volvo > Snuze: Needs another Swede 11/05/2020 at 10:12

1

Regarding hard starting...I’d rent a fuel pressure test kit and hook it up to the schrader valve on the fuel rail. I wonder if the pump is weak.

Snuze: Needs another Swede > Sovande 11/05/2020 at 10:30

1

I saw that same list, and definitely going to check that stuff out. I’m trying to avoid just firing the parts cannon at the car.

I replaced about 50% of the vacuum hoses when I did the flame trap service. Guess I need to replace the other 50%.

Snuze: Needs another Swede > cmill189 - sans Volvo 11/05/2020 at 10:32

0

The winter blend fuel thing is interesting... I’m going to update my post above.  

I’ve messed with the blend, it seems to be functioning fine. I’m kind of wondering if I have a thermostat issue. They are really cheap, I may just get one and throw in it for the hell of it. I hate firing the parts cannon, but in this case its only a few dollars.

Sovande > Snuze: Needs another Swede 11/05/2020 at 10:35

1

I figured you had. I think your problem sounds like the coolant temp sensor. I would start there and see what you find. I can't imagine the part is overly expensive? The problem with these engines is that they will run relatively well with all kinds of broken shit which makes figuring out what's wrong a pain in the ass.

Snuze: Needs another Swede > Sovande 11/05/2020 at 10:41

1

“A V olvo will run like shit longer than most cars will run”

I remember you telling me that and it still cracks me up. And it’s still true.

I’m also intrigued by Cmills story, above, that his XC90 did this same thing, but only on winter blend gas. I updated my post with the fact that the last time I drove the car was early September.

I think I’m going to clean my MAF, check my hoses, and take a look at the thermostat/coolant temp sensor housing. 

Snuze: Needs another Swede > cmill189 - sans Volvo 11/05/2020 at 10:45

1

I think I have a couple different issues going on here, and the hard starting may not be related to my CEL . It was hard starting for a while, and this summer when I did the rear suspension, I noticed some damaged breather lines in the fuel system, so I replaced those, and it got somewhat better. The battery died back in August/September, so I replaced that. But it’s still not great, so I’m thinking either still a fuel issue, or possibly the starter going out.

Sovande > Snuze: Needs another Swede 11/05/2020 at 11:02

1

I missed that post. Interesting. Get it warm and do an Italian tune up and see what happens? It can’t hurt, unless it does, I suppose.

I’m kind of on the hunt for another C30...

Bandit > Snuze: Needs another Swede 11/05/2020 at 11:05

0

I had a similar issue with similar symptoms on my project Mustang, turned out the cats were clogged up/broken. Good luck! 

Snuze: Needs another Swede > Sovande 11/05/2020 at 11:11

0

The C30s are neat little cars. My grandparents neighbor had an old P1800 wagon, which I thought was beautiful when I was a kid, and I love how the C30 captures the details of that car .

I’m still waffling on a Cruze replacement. Part of me wants something stupid like a GT350 or Camaro SS. But the more practical side of me is leaning towards either a small pickup (like a Colorado) or a V60 CC. If I go V60, I think I’d get a 2015-16 that still has the inline 5.

I already have the perfect V60 CC “rally” build planned out in my head - different wheels, chunkier tires, some rally lights on the front. I’ve found an exhaust for it, but not much in the way of a tune.  Heico offers one, but it’s like $1500, which seems steep for a canned tune.  

Jb boin > Snuze: Needs another Swede 11/05/2020 at 11:11

1

If it’s like a VW product, the temperature gauge is not 1/1, its locked at 90°c between ~85 and 95 °c if i recall correctly so having the needle at 80° meant it was rather around 75° .

Use your OBD2 tool to check the temperature when driving and how fast it goes up but if the thermostat is more than 15 years old, it’s safe to change it ; if it has not failed yet it will soon and might do it gradually (making it hard to know if it’s failed or not as the car will still be able to get up to temp but slowly ) .

If you are sure that the blender motor is ok, t he other possibility is that the heater core is clogged up or that there is an air pocket at the top or your coolant circuit which is usually around the heater core.

If it’s clogged , it’s usually quite efficient to simply run a hose with tap water on reverse (on the exit of the core), i did that last winter with my A4, it wasn’t excessively dirty but it still cleaned up some crud (unfortunately i only have a picture with foam of the first clean so it’s hard to see how dirty it was ) :

It’s what was still going out after running multiple buckets :

I n my case, the coolant reservoir (and the coolant itself) was quite dirty when i bought the car (which is why i did the cleanse) and i also had one of the blender motor locked in closed position   :

Sovande > Snuze: Needs another Swede 11/05/2020 at 11:17

0

You won’t get much more out of the 5 cylinder than what the Polestar tune does, I don’t think. Hilton Tuning is a guy who offers tunes for all the engines. His tunes are custom and kind of pricey, in that $1500 range. I’m going with Polestar for mine because it’s cheaper.

I like cars: Jim Spanfeller is one ugly motherfucker > Snuze: Needs another Swede 11/05/2020 at 11:26

0

The last thing, and I just caught this randomly in a forum, is a bad Engine Coolant Temp sensor and/or thermostat.

If the oxygen sensor is still giving a valid output, this is very possible.

Here’s a short primer on how fueling is done with closed loop control. In a modern EFI system (when I say “modern”, I mean pretty much anything digitally controlled), there are various sensors giving feedback to the ECU. In most EFI, that includes at least one oxygen sensor , coolant temperature sensor , intake air temperature sensor , mass air flow and/or manifold absolute pressure sensors . In order to inject the appropriate amount of fuel , the ECU needs to know the temperature of the air coming in (IAT), how much air is coming in (MAF/MAP), the temperature of the combustion chamber (coolant temp sensor data is extrapolated), and the fuel content of exhaust gasses. When the engine is first started, the oxygen sensor data generally doesn’t affect fueling, as the sensor is still warming up and not giving “real” data . The ECU takes the data from MAF, MAP, IAT, and CTS to achieve a rich mixture until the oxygen sensor control loop “closes” when the sensor is warmed up.

When the oxygen sensor control loop closes, i f your ECU sees a signal from the oxygen sensor that the exhaust gases have too much fuel in them, the fuel delivery is reduced to compensate. When the result is that there is still too much fuel in the exhaust, that means one of two things- either the oxygen sensor is bad, or the fueling was adjusted incorrectly. Narrowband lambda sensors generally only give an output of “lean”, “rich”, or “stoichiometric”- it doesn’t tell the ECU how rich mixture is, just that it is rich.

If the ECU receives incorrect information from the other sensors, it will incorrectly adapt fueling . I would look at your MAF again and maybe replace the coolant temp sensor.

Snuze: Needs another Swede > Sovande 11/05/2020 at 11:57

1

I’m not looking for anything crazy. The CC is 250 HP, a bump to like 300, combined with a nice sounding exhaust, would be perfect for me. The problem is I don’t think the Polestar offers a tune for the V60 CC with the I5, for whatever reason.

Snuze: Needs another Swede > Jb boin 11/05/2020 at 11:59

0

Interesting. I replaced the water pump last year, and I flushed the system then, and it seemed okay . I do get heat out of the thing... a lot of heat in fact, it just takes forever to get to that point. The heat worked as expected last winter, and it seems like it’s just taking way longer to get there this year.  I may go ahead and throw a thermostat at it to be safe.  The car is 24 years old and I have no idea if it’s ever been replaced.  

Sovande > Snuze: Needs another Swede 11/05/2020 at 12:28

0

Look up Hilton. Looks like about $1000 for a stage one tune and $1250 for stage 2 which requires a bigger intercooler. I bet that puts you close. So for about $2000 you could get there. 

Jb boin > Snuze: Needs another Swede 11/05/2020 at 12:35

0

If it’s like the A4, the highest point of the circuit is at the top of the heater core which means that if you flushed your circuit and didn’t bleed it there you might have an air pocket here, making the water flow with less pressure here (or even not at all ), here is how it looks on the A4 :

But the video is not to be followed as he is doing what should not be done : bleed with the engine running ( or the coolant hot) as it will suck air instead of bleeding it...

Snuze: Needs another Swede > I like cars: Jim Spanfeller is one ugly motherfucker 11/05/2020 at 12:37

0

My plan is to pay more attention to the data on the way home from work today to see if I can suss out anything else. Then I’m going to recheck my MAF and vacuum hoses. I hate firing the parts cannon but I may also just throw a thermostat in for the heck of it, they are cheap and the car is 24 years old and I have no idea if it’s ever been changed before. 

I’m fairly familiar with the basics of fuel injection systems, my focus in undergrad was powertrain engineering . But in this case I’m getting some unusual symptoms that don’t seem to point directly to a particular component. So I’ll just collect more data and analyze. But Oppo is always super helpful and I appreciate your insight and that from everyone else in the thread. 

Snuze: Needs another Swede > Bandit 11/05/2020 at 12:39

0

Oh, please, no. 

Snuze: Needs another Swede > Jb boin 11/05/2020 at 12:42

0

Good point, I’ll definitely keep that in mind.  To be honest I may be dealing with a few different issues here (hard starting, the CEL, and the heat).  

I like cars: Jim Spanfeller is one ugly motherfucker > Snuze: Needs another Swede 11/05/2020 at 12:43

0

Thermostat wouldn’t cause this. It’s entirely a mechanical component. If it’s failed open, your block will just be cooler than it’s supposed to be, but your coolant temp sensor will still compensate for it.

If the thermostat isn’t bad, don’t replace it just for being old. There’s a high likelihood of new coolant leaks every time you unbolt a water fitting.

Snuze: Needs another Swede > Sovande 11/05/2020 at 12:48

0

I’ve heard of them and will give them a look. I also saw the TDI box, but that appears to be a piggyback, which I’m not as crazy about, even if it is cheaper. I guess if you want to modify a fine european luxury estate, you gotta play with the big boys.

Is your V60 an I5, I6, or does it have one of the newer DriveE engines?

Sovande > Snuze: Needs another Swede 11/05/2020 at 12:54

0

Mine is a drive e. I like it and in sport mode it’s quick enough. The normal mode leaves a little to be desired because the transmission tries to keep everything under about 2200 rpms and doesn’t like to downshift but prefers to just drop it in neutral off throttle. It sounds awful though. It's not a good sounding engine at all. But on the highway it gets a legitimate 37 mpgs and I have the flappy paddles if I get bored.

I looked at the tdi box too, but since they don't publish actual numbers I'm not sold. The Polestar tune for my car is basically just a transmission remap which people say makes a huge improvement. 

Snuze: Needs another Swede > Sovande 11/05/2020 at 13:06

1

The TDI box also doesn’t do anything with the transmission, as far as I know, which is another reason I’m more interested in an actual tune.

I used to consistently drive 25k/yr, but in the last few years its been about half that , and I don’t see relocating or changing jobs anytime soon so mileage is less of a concern to me these days. That being said, the Cruze averages 35 mpg in mixed driving , and not spending all my money on gas is nice. The older I5 V60s are rated at like 20/30, which would be livable. The pony cars I’ve been looking at, and the truck, are all around 16/24. Oof.