[octaviab]

Hi everyone.

I am still having CEL light and DTC P0101 Secondary U040168 pointing to a bad Mass air flow sensor. However, I replaced the MAF sensor, but the same CEL/DTC light is back. There is no obvious difficulty starting and cruising at highway speed, but the vehicle overall drives with low power comparable with my go to Gen 3 Prius .
I have run out of ideas, so I have dropped the vehicle for diagnose at Volvo dealership in Gilbert Arizona. After a day of waiting Volvo sent me a text recommending to start replacing front and rear Oxygen sensors, estimate $1200. I am very concerned about the overall suggestion to replace 2 sensors and the fact they do not sound very reassuring this experiment will fix the problem stating "re-test following repair"
I am not sure what to do...I can can get both DENSO OEM sensors for $400 online or even buy cheaper BOSCH aftermarket which seems compatible with Genuine Volvo. Is any re-adaptation needed to calibrate after sensor replacement ?
2016 S60 46k miles 2.0 T5
This my first Volvo and ongoing stressful experience to fix it.
Any other ideas on what would be the best way forward.
Thanks much!
Octavian

 

[octaviab]

Some of the 2016 4 Cyl engines did have to have the front 02 sensor replace. An air intake leak after the AMM will also set a P0171 and/or 02 code. Inside the red circle is a one way check valve. Hose 4 or 5 goes from the oil trap 1 to this one way check valve. This is how engine oil vapors get re-burnt back into the engine. This one way check valve will become coated with oil vapor gunk and not seal at idle. This can set the code. #1 PCV box valve will fail and set the same code(s). If the engine S/N label is on the top of your pcv box, it is original. Pcv box 1 has a high failure rate.
You need to replace #14 pipe to get the check valve. Hose 4 or 5 will crack where it goes into the check valve. The above is the same for a supercharger engine. You may end up replacing all 4 parts, 02 sensor, #1, #14, #4 or #5 to keep the light off. Also, you need to go into VIDA, ECM adaptations and reset the adaptation values. A battery cable reset should be done also, this will erase the stored short term memory. The only way to test the one way check valve is smoke test thru hose 11 and see if smoke exits out thru the one way valve. You can remove the hose at the check valve. If you see dirty oil gunk on the one way valve, replace fresh air pipe #14. Do not use these part #'s to order parts for you car. Let the dealer order parts using your VIN.

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Thanks much for the detailed reply and useful insights. The only DTC present is Primary P0101 Secondary U040168. The Tech verified there is stored fault for system too rich on Bank 1, High pressure fuel pump OK, fuel trim OK, no misfires present. The engine look pretty clean, PVC seems original and has been serviced in time by Volvo dealership since day 1. No noice or other related symptoms pointing to oil trap. Is safe to say to start replacing the front O2 Sensor 1 ? Is this the sensor that measures the air/fuel ratio getting into or coming out of the engine.? Or should I replace both sensors and check valve you have mentioned ? TIA

 

[octaviab]

Many thanks for such detailed reply and useful insights. To summarize, the only DTC present is Primary P0101 Secondary U040168. The Volvo Tech verified there is a stored fault for system too rich on Bank 1, High pressure fuel pump OK, fuel trim OK, spark plugs OK, no misfires present. The engine looks pretty clean, PVC seems original, this vehicle has been serviced in time by Volvo dealership since day 1. No noise or other related symptoms pointing to oil trap diaphragm issue. Would be safe to start replacing the front O2 Sensor 1 ? Is this the actual sensor that measures the air/fuel ratio getting into or coming out of the engine.? Or should I replace both sensors and next check valve you have mentioned ? TIA

 

[octaviab]

Meanwhile, I have bought the upstream O2 sensor 32253665 from Volvo, swap it and run adaptation, but still the CEL light on showing the same DTCs MAF P010100 and P017200 Bank 1 too reach problem. persists. I’ll go back to Volvo and ask them to take a closer look, but did non have the energy yet. Any other ideas are welcome. TIA