1996 Volvo 960 P0172 OBD Code

Volvo2009 · Post by **Volvo2009** » 24 Jan 2009, 17:38

Bill,
I read some of your responses to similar question. (P0172 System too rich Bank 1)
my car has 120K miles (230K km). I already cleared the code before, but it keeps reappearing.

few Q's
1. How many Oxygen sensor these cars have. (some say only one, other claim 2)

2. Since these bloody parts are expensive, is that possible to clean the heads with metal brash, or chemical, for them function again.

3. Are there any other causes to which you can think of. ( I already cleaned the MAF, and checked the vacuum lines.

Appreciate reply thanks

Post by **billofdurham** » 25 Jan 2009, 12:23

Welcome to Matthew's Volvo Site.

1. There are two on the '96 model. From '92 to '94 there was only one.

2. I don't know of any cleaner and would not recommend a wire brush. This is how one of these units works, courtesy of HowStuffWorks:

The oxygen sensor is positioned in the exhaust pipe and can detect rich and lean mixtures. The mechanism in most sensors involves a chemical reaction that generates a voltage (see the patents below for details). The engine's computer looks at the voltage to determine if the mixture is rich or lean, and adjusts the amount of fuel entering the engine accordingly.

The reason why the engine needs the oxygen sensor is because the amount of oxygen that the engine can pull in depends on all sorts of things, such as the altitude, the temperature of the air, the temperature of the engine, the barometric pressure, the load on the engine, etc.

When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. Your car performs poorly and uses more fuel than it needs to.

No amount of cleaning with a wire brush is going to restore that.

3. Low or high fuel pressure; leaking injectors; leaking EVAP system; contaminated engine oil; oil level too high.

Bosch recommend that heated sensors are changed every 60,000 miles. Of course that increases their profit but the sensors don't last forever.

Bill.

Volvo2009 · Post by **Volvo2009** » 25 Jan 2009, 16:14

Bill,
thanks again for the reply. Got it.
I have one more question of this subject. I don't expect to keep the car for too long (maybe another 10K) before selling it. So it is natural I will want to get by as cheap as possible.

This site
http://www.autopartswarehouse.com/searc ... 4294965671

has variety of sensor, with big gap between the prices (I realize the axiom "you get what you paid for").
What is your opinion about the generic $42 vs. the Bosch?. ( I can solder the wire?

thanks again

Post by **billofdurham** » 26 Jan 2009, 12:10

I agree you get what you pay for. If it lasts 10,000 miles and you have sold the car you did get what you paid for.

The reviews are good. I noticed there were none for the Bosch so they probably only sell the cheaper version which is what I would have bought.

Bill.

Volvo2009 · Post by **Volvo2009** » 29 Jan 2009, 12:20

Bill,
This outlet
http://www.car-stuff.com/store/?N=11876 ... 11921+9167

has the same parts, but cheaper. They offer 2 Universal parts. A 2 wired (USOS-2000) and a 3 wired (USOS-3000) one.

Which one would fit my car?. (I have never had to replace the O-Sensors before, so I am somewhat in the dark).

Appreciate some clarification here.

thanks

Post by **billofdurham** » 29 Jan 2009, 12:37

The oxygen sensors on your car are heated so you need the 3 wire version.

Bill.

Volvo2009 · Post by **Volvo2009** » 29 Jan 2009, 17:05

thanks Bill.