Startability/Drivability Problem Engine Light On Code P0172

chn718 · Post by **chn718** » 21 Apr 2008, 17:45

Hi all, I recently bought a 97 Volvo 850 wagon with 150,000 miles on it, recently it has been having problems starting, I would need to turn the key once and the engine would crank, but it would not start, if I let it go and then crank it again it would start, sometimes 2-3 times. I took it to my mechanic and he said the spark plug wire was shot/burnt and so he replaced all the spark plugs and the spark plug wire, and distributor cap I believe, or whatever else is related to the spark plugs. It started but still took two cranks, and recently the check engine light just came on while I was driving it, I took it to autozone and the guy read the fault code P0172, now when I was just driving back from Autozone, the car lost power and it feels like there is no power, also the car stalled and I had to restart it. According to the autozone print out it says that I have a problem with either a oxygen sensor is defective, fuel injector problem or there is a ignition misfire-repair.
First I live in Minneapolis, MN, should I take it to the dealer to fix this, will individual mechanic be able to diagnose this, and how much will each of these problems cost as well as how likely each culprit of the problem is?

Post by **MadeInJapan** » 21 Apr 2008, 17:58

Typical Bank 1 fuel trim code showing that your front 0xygen sensor is reading too rich of a gas mixture. Check all of your small vacuum hoses for cracks. These cars are very picky about air/gas mixture... a hose leak and the ECU compensates by adding more gas. Maybe the mechanic in doing the plugs and wires pulled a hose off or damaged one? Look all around where he was working from the distributor cap up to the top of the engine and the sides of the engine as well where there are a couple of small 90degree rubber elbows (places prone to breaking). If that's not it it truly could be an oxygen sensor especially if it's never been replaced before but the coincidence is a bit remarkable that it would happen after new plugs and wires were installed (unless of course terrible after market wires and wrong plugs or the wrong plug gaps were used). Post up what he replaced your plugs and wires with...Volvo's are very specific as to what they like and don't like.

chn718 · Post by **chn718** » 21 Apr 2008, 18:15

Thanks for the help, but a few more questions, first how do I know what kind of wires/plugs he used? He said they were purchased from the volvo dealer, second could it be the fuel injectors? Since I feel the car lacks power, and there is problems starting, or can this also be attributed to oxygen sensor? I have 150,000 miles is it possible a leak in the hose can cause all of this?

Thanks

Post by **MadeInJapan** » 21 Apr 2008, 18:27

Yes a leak in the hose can and will cause all of this. If they are official Volvo wires (made by Bougicord) then you're good on the wires. The Volvo plugs for your car are also fine. If a turbo there are specific plugs for that...if not, then there are specific plugs for that as well. They still should be gapped correctly although a few mm difference in the gap won't do all of this. Fuel injectors don't typically cause a problem like this suddenly...it happens slowly. If you feel your plugs and wires are fine then I would go the fuel pump relay route...these are known to go bad suddenly.