P0305, P0172 and P0131, on a 1998 C70 turbo

eddiecohoon · Post by **eddiecohoon** » 07 Apr 2012, 01:22

The shops in my area dont handle Volvo much and the cant seem to find the issue. They also dont want to just dig because they dont know if they can even figure it out. I just had a new o2 sensor put in and the code came right back on the next day. I also changed the spark plugs and ran injector cleaner through it. The most the shop gave me was that its staying in open loop at all times. It has the 2.3L 5 cylinder with a turbo. 172000 miles.

MilehighV70XC · Post by **MilehighV70XC** » 07 Apr 2012, 09:44

Do a search for that code on this site. There are plenty of post about code 172. What most the the post say are check for vacuum leaks and the MAF sensor.
I am in the same situation. I have replaced the front O2 and my car, and still getting a similar code. I am pretty sure on my car it is a vacuum leak I am going to be tracking down today.

Post by **erikv11** » 07 Apr 2012, 09:48

What brand of O2 sensor was put in? These cars do not do well with brands other than Bosch with OEM connector (Bosch part # 15097 for front O2 sensor).

Also check carefully for vacuum leaks, end of the intake manifold for sure but preferably with a can of starting fluid.

And finally, sometimes a bad MAF can cause the ECU to throw the 131 and 172 codes. Also having a 305 (misfire cylinder 5) is a bit odd. For sure clear the codes and see which ones come back.

electech · Post by **electech** » 13 Apr 2012, 00:52

Are you sure it was a 305 and not a 505? I see those two together a lot...505 means idle air trim. Look at the vacuum and the EVAP systems.

If it was 305, and it keeps coming back, that needs to be fixed first. Can't diagnose an engine that's misfiring. That is an ignition issue...start with the plugs and work back. If you replace the plugs, be sure to use Volvo OEM plugs. When you fix the misfire, the O2 sensors will behave quite differently.

eddiecohoon · Post by **eddiecohoon** » 16 Apr 2012, 16:27

So i have updates. to go with what i have replaced, I have now also done the rotor and the distributor cap. Felt it was still misfiring but drove it around the block to see what codes can back on. The misfire 305 was still there without the 131 o2 sensor or the 172. However code 108 MAP sensor came on. I found some posts on here that say the MAP sensor does nothing unless you live in high altitude. So should i just ignore it and worry about my misfire then come back to it after the fact? And whoat should my next step be for the misfire, Plug wires?

Post by **erikv11** » 16 Apr 2012, 18:35

Yeah, I would sort out the 305 first.

Wires is not a bad guess, but expensive to replace if they are OK. They usually last a very ling time. What is the date code on the wires?

What brand of spark plugs was put in?

Post by **jblackburn** » 16 Apr 2012, 19:00

Ignore the MAP sensor for now but the damn thing will keep throwing check engine lights at you until you replace it. Junkyards are a great source for that.

Troubleshoot the misfire code, and then the p0172 and other are almost certainly tied to a vacuum leak. Check the elbow behind the power steering pump on the intake manifold.

eddiecohoon · Post by **eddiecohoon** » 17 Apr 2012, 18:48

new update.... So i have now replaced the plugs, plug wires, rotor and distributor cap. The only codes it sent after the wires, which was the last thing I did, was 305 and 131. Could a clogged catalytic converter be the cause for both of these codes? mt cat has visible heat coming off it after just a short drive around a couple blocks. Also smells like something is burning.

Post by **erikv11** » 17 Apr 2012, 21:39

What brand of spark plugs was put in?

eddiecohoon · Post by **eddiecohoon** » 18 Apr 2012, 04:14

Autolite