[bsmith2019]

Hi everyone,

First off, would like to thank this forum for all of the great information regarding my S60. This forum has been great reference material for the many many repairs on my Volvo. You guys are great.

Some background on my Volvo:

-2006 S60 2.5T AWD (My first Volvo!)
-Purchased used with 219k mi. - now has 234k mi. (shooting for 250k!)

The Problem:

In the past few months, I've had a recurring set of trouble codes being thrown. I will attach a picture of the code list.

When these codes are thrown, I lose any kind of high idle on cold startups and experience a jittery, stumbling idle. Sometimes it gets bad enough that it wont stay running when started. The aspect that I don't understand is whenever I clear the codes, the car reverts back to normal and runs great for a few drive cycles until the codes are thrown again.

My first decision was to replace the Mass Air Flow sensor, with hopes that a new sensor would clear up the air and fuel related codes. I purchased a brand new OEM Bosch unit from FCP Euro and installed it, but no luck. Same codes were being thrown. The codes start out as the 120D and 121B pair, and then the long term fuel trim codes are thrown if I try to drive it with the first two codes present.

After researching the 120D Air Mass code, I found that it could be related to a faulty intake air temperature sensor. To be honest I didn't find many results for an IAT sensor for my year S60, but I concluded that it was integrated into the boost pressure sensor. (Honestly not sure if that's even correct, I was getting desperate at this point.) Anyway, I removed my old one and installed a new Bosch unit from FCP Euro. No dice. Same codes.

From my understanding, (please correct me if I'm mistaken) clearing diagnostic codes does not reset the fuel adaption data (short term and long term fuel trim data). The only system that I'm aware of that changes from clearing trouble codes would be the readiness monitors. So I checked to see what monitors had been successfully passed when my engine light comes on, and the only monitor not complete was the EVAP monitor.

I suppose the thing that bothers me more than the check engine light itself is the fact that I don't know why clearing the codes would allow my car to run fine for a few drive cycles. Is it some kind of weird drive cycle / readiness monitor condition? If it was a physical issue, (sensor failure, bad wiring, etc.) that causes the codes, why would a simple code clear fix the issue for a short period of time? Like I said, when the codes aren't being thrown, the car runs great, good power & acceleration, no hesitation.

Has anyone else dealt with these codes before? I'm basically pulling my hair out on this one.

Any help would be greatly appreciated.

Thank you,

Bradley

 

[Phixion]

If you can have a VIDA scan of the codes and faults, that will give you an almost direct answer to exactly what's going on. Almost because it's far more focused then an OBD code. As for starting normal and then the issue showing up tells me that it's related to one of the readiness monitors that usually take a few start or drive cycles to set which is when a check engine light will come on and limp home mode engage depending on the issue. Since EVAP isn't being set yet (can take a loooong time in our cars) I'm betting it's when the catalyst monitor sets since the other monitors set upon initial start with a reset ECU.

Have you cleaned your MAF sensor? One that's dirty can cause eons of weird issues and codes and you have 2 related to that. Also try running the car with the MAF unplugged when the code sets or after resetting to see if that helps. I'd the MAF isn't dirty, it could just be bad. I've had to replace mine on my '04 S60 at around 160k'ish miles. I know a MAF code was coming up, but no reduced power or performance that I recall.

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[bsmith2019]

If you can have a VIDA scan of the codes and faults, that will give you an almost direct answer to exactly what's going on. Almost because it's far more focused then an OBD code. As for starting normal and then the issue showing up tells me that it's related to one of the readiness monitors that usually take a few start or drive cycles to set which is when a check engine light will come on and limp home mode engage depending on the issue. Since EVAP isn't being set yet (can take a loooong time in our cars) I'm betting it's when the catalyst monitor sets since the other monitors set upon initial start with a reset ECU.

Have you cleaned your MAF sensor? One that's dirty can cause eons of weird issues and codes and you have 2 related to that. Also try running the car with the MAF unplugged when the code sets or after resetting to see if that helps. I'd the MAF isn't dirty, it could just be bad. I've had to replace mine on my '04 S60 at around 160k'ish miles. I know a MAF code was coming up, but no reduced power or performance that I recall.

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I will have to see if I can access a VIDA scan tool somehow. Would be awesome to have it point me in the right direction. And yes I agree with the readiness monitor limp condition. That's the only possible thing I could think of being a factor. I will definitely research the catalyst monitor and figure out what systems its checking and what conditions have to be met.

Yes, I have tried cleaning my MAF sensor with no luck. I should've mentioned this in my first post, but when I first purchased the car @219kmi., it was throwing a singular MAF code (most likely the same one you experienced @160k). I bought a new Bosch unit and that totally fixed that problem. When I got this new set of codes, I purchased yet another MAF sensor to try (the one I'm referring to in my original post). Neither of the two new sensors have resolved my issue .

I will try the MAF unplugging test next, thank you for the recommendation. I'll keep the thread updated.

Thank you for your reply!

 

[Phixion]

You're welcome and good luck! Keep us updated and we'll help you out as best we can. Also there's a thread for the location of members with VIDA willing to scan other member's cars with it, so you can see if there's any near you.

Seems like the MAF isn't you issue then, but try unplugging it anyways for giggles too see if that helps any. I'm racking my brain what else might be causing what you're experiencing....

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[vista88]

		MAF-120D and MAF -121B flow too low are both typically caused by a dirty/clogged throttle body combined with a clogged PCV system and/or a leak in the intake system-not by a "bad" or dirty MAF. This condition will also often set fuel trim codes.​ You can erase ECM DTC's and reset adaption by pulling the 5 amp fuse in position 23 in the engine compartment fuse panel for about 10 minutes.

 

[bsmith2019]

		MAF-120D and MAF -121B flow too low are both typically caused by a dirty/clogged throttle body combined with a clogged PCV system and/or a leak in the intake system-not by a "bad" or dirty MAF. This condition will also often set fuel trim codes.​ You can erase ECM DTC's and reset adaption by pulling the 5 amp fuse in position 23 in the engine compartment fuse panel for about 10 minutes.

[PROBLEM SOLVED]

Thank you for your reply! I wanted to touch base with this thread with my findings regarding my issue. I'm happy to say the problem has been solved. I built a DIY smoke machine and checked for intake leaks. Luckily I didn't find any so I was able to rule out unmetered air being an issue. I bought a used throttle body from a salvage S60 at a local pick and pull, cleaned it until it was spotless, and installed that with a new gasket. After tearing down the old throttle body, I found a chipped gear tooth and lots of oil and grime. I have a couple days on the new(used) throttle body and I'm thrilled to report its been flawless so far. I will have to take some pictures of the old throttle body and post them here.

Thanks for the help!

DIY smoke machine can bee seen on the table to the right.

Video I used to build smoke machine -

 

[kyngofpop]

You're welcome and good luck! Keep us updated and we'll help you out as best we can. Also there's a thread for the location of members with VIDA willing to scan other member's cars with it, so you can see if there's any near you.

Seems like the MAF isn't you issue then, but try unplugging it anyways for giggles too see if that helps any. I'm racking my brain what else might be causing what you're experiencing....

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Where is the thread with VIDA users close by? I’d like to buy my own unit but don’t wanna creat another thread before I do my search. VIDA/DICE is so confusing to me but I’m willing to purchase my own unit, just don’t know where to begin.

Sorry to thread hijack but it seems that I’m gna be in this Volvo thing permanently and need diagnostic hardware.


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[bsmith2019]

Where is the thread with VIDA users close by? I’d like to buy my own unit but don’t wanna creat another thread before I do my search. VIDA/DICE is so confusing to me but I’m willing to purchase my own unit, just don’t know where to begin.

Sorry to thread hijack but it seems that I’m gna be in this Volvo thing permanently and need diagnostic hardware.


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VIDA/DiCE Locator Thread

Dallas - 2014D Sent from my iPhone using Tapatalk Thanks! PMed you for help in Dallas :)

www.swedespeed.com

Should be the link you're looking for.

Best of luck and Happy Thanksgiving.