1997 - 850 DPT P0172,0410, and 0440

flat_tomato · Post by **flat_tomato** » 02 Oct 2014, 07:31

Hi Everyone,

I've recently become an owner of a 97 850 (just married, it was my wife's car when we got married and we've switched cars). The check engine light recently came on and I got all three of these diagnostic codes: 172 - Long term idle air trim, 410 - secondary air injection system malfunction, and 440 EVAP system. I'm not particularly familiar with any of these things, is there a problem that connects the three of these things? Also aside from a reduction in gas mileage/more emissions, how likely would this be to turn into a serious problem? Thanks for the advice all!

Post by **Ozark Lee** » 02 Oct 2014, 08:00

Welcome to MVS,

The codes you listed fall into the "Not a huge problem" category although they are not really related to a single problem.

The P0172 code is typically caused by a vacuum line leak. The usual suspect is a vacuum elbow that very inconveniently located behind the power steering pump on the end of the intake manifold. One of the other moderators, Justin, has a great picture of it but I can't seem to locate the thread.

The P0410 is an error in the Secondary Air System. Typically that is due to a bad blower motor and it is insanely expensive to replace. Fortunately the system can be eliminated and the ECU can be tricked into thinking it is fully functional by soldering in a cheap (under $1.00) diode.

Here is a link to the SAS delete thread in the repair database:

https://www.matthewsvolvosite.com/forums ... =1&t=31536

The picture in the first post is wrong, keep reading.

The P0440 can be as simple as a bad gas cap but usually it is a rotted out vacuum line back by the gas tank at the rollover valve. There are dozens of threads for the various failures in the EVAP system. Search the repair database and then the whole site for "EVAP" and it will bring up a number of threads with some good pictures and procedures.

None of these codes will keep the car from running, it just won't run at peak efficiency.

...Lee

flat_tomato · Post by **flat_tomato** » 06 Jan 2015, 12:16

Hey Lee,

I meant to send this awhile ago but I wanted to say thank you for the help. Your info on the vacuum line leak was spot on, a pain to get to but it was there alright. On the last one I lucked out - swapped out the gas cap, cleared the code and haven't seen it since.

Thanks again!
SH