2009 XC70 T6 OBD Code P0172
 

The motor light came on in my 2009 XC70 T6. Everything is running fine. I checked the code in other Volvo forums and there seems to be quite a bit of buzz.

The P0172 code translates to "System Too Rich - Bank 1". Basically this means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Symptoms: "You will more than likely not notice any drivability problems, although there may be symptoms such as a misfire". I have none of these.

Causes: A code P0172 may mean that one or more of the following has happened: The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry. There could be a vacuum leak. There could be a fuel pressure or delivery problem.

Possible Solutions: Inspect all vacuum and PCV hoses, replace if necessary Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling Inspect fuel lines for cracks, leaks, or pinches Check the fuel pressure at the fuel rail Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced. Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

1. oxygen sensor
2. air mass inflow
3. vacuum (hoses and elbows connectors)

My Volvo Mechanic ran diagnostics. He has replaced all 6 plugs. He is also replacing the oil trap. None of these are mentioned anywhere in the buzz I have been reading. I feel he thinks he is in a Volvo Diagnostic Casino pulling on the 1-arm bandit for answers.

Has anybody else run into this problem on their XC70. If so, what was your fix.

Frustrated in Pickering Ontario Canada

P0172 Problem Update
 

My car has been offline for 2 days now. In an attempt to replace the suspect source of the problem, the oil drain, which they believe had a defective diaphragm, they discovered the air hose located between the engine block and the firewall that connects to the turbo, was defective and leaking. The part was ordered yesterday and is being delivered tomorrow morning. The original oil drain will be remounted as the new one is no longer required now. This defective hose renders the car inoperable.

Evidently this leaking air hose for the turbo is affecting fuel/oxygen blend and is responsible for triggering the motor light on the dash and the underlying P0172 code.

Fingers crossed.

Barry:confused:

P0172 Problem Update
 

The split air hose for the turbo was replaced but it did not turn out the trouble light.

The oil drain pan located at the back of the engine near the firewall, was also replaced. Apparently the diaphragm was defective. Once this was replaced, the light went out and the car is running better than it ever has.

Case closed.