Hi All,

I have 1996 850 GLT and last week my check engine light came on and the car isn't running right. The car won't idle right, it keeps revving up and downwhile idling and almost shuts off (sometimes it shuts off completely). I took the car to autozone and had them read the code. The code that they pulled said "P0172 - System running too rich". Could this be the primary O2 sensor? I was wondering if there is something else that I should check before buying the O2 sensors in case it isn't the O2 sensor. Any leads?? Any help would be greatly appreciated. Also, if it is the O2 sensor, where is the O2 sensor located?

Thanks,
GLTOwner

 

Hi GLTOwner,

Sorry about the problem, it must be annoying.

When was the last time your car had a good tune-up? If the ignition system has never received a tune-up, the fuel may not be burning efficiently.

If it turns out that the O2 sensor (s) is shot, which is common for cars with many miles/years, the location depends on the engine; turbo-engine has 2, and NA (non-turbo) has 1. Either way, O2 sensor is located somewhere along the exhaust pipe, rather closer to the engine.

I once had similar code; O2 sensor slow response. I reset the code twice, the first time I reset it the code came back in about 2 weeks, but the 2nd time I reset it, the code never returned.

They may be of reference:
http://volvospeed.com/Repair/o2sensor1.php
http://volvospeed.com/Repair/a2.html

If the engine is idling rough, it could be due to a number of reasons and without actually testing the car myself, I can only give you some possibilities:

1. Electronic control problem. Loose electrical connections or faulty sensors.
2. Tune-up related (spark plugs, ignition wires, distributor cap & rotor, fuel filter, air filter, throttle body needs cleaning, fuel injectors, etc...)
3. The engine may need to re-learn idle, if the battery has been disconnected recently.
4. Faulty alternator/battery (you can briefly check them with a digital multimeter).

If it turns out that the O2 sensor is actually causing the problem, buy an OEM (Bosch) sensor. Volvos are extremely sensitive to the quality of parts.

Also, let us know if your car has a maintenance record, as well as the mileage of it.

I hope this helps.


JPN

 

Hi again,

Someone else has had a similar problem in the past, I'll post the URL:

https://volvoforums.com/m_51158/tm.htm

In this case, the culprit seems to have been the MAF sensor, so it may have been a different situation than yours but worth a read.

Good luck,


JPN

 

Thanks JPN, for the quick response. And thank you for all the good tips and leads. I will check them out. My car has 250K on it and has had regular maintenance done on it. (not sure if the O2 sensor has been replaced though -since I bought it used when it had 243K on it).

-GLTOwner

 

Please let us know your findings.

Cheers,


JPN

[IMG]local://upfiles/6892/B11589B0372A4CD1B04F78D9362AB8DA.jpg[/IMG]

 

Cheers!! It was the Mass Airflow Sensor which I was able to get from a pull it yourself for $30 as opposed to $315 for a new one. My only regret,taking it to the mechanic to have it diagnosed just in case it wasn't the MAF. It ended up costing me $120 ($90 for diagnosis + $30 for the part). Anyways, the car runs pretty good now. I will have to take it to autozone to get the CEL cleared. I'd like to thank you JPN for your generous contribution and the knowledge that you have shared with me regarding this issue. Keep it up!!

Thanks
-GLTOwner

 

Hello GLTOwner,

Glad you found the problem & corrected it.

I consider the $90 as a learning fee, and I believe it was worth it to learn your car better.

Good luck to you & your GLT.

Sincerely,


JPN