How Cleaning a MAF Sensor Can Save You Money (P80 Volvo)

While on a long road trip from Connecticut to Florida, my Volvo S70 illuminated a check engine light after I had arrived and started the car the following day (it had been sitting all night). I was stumped as to what it could be because the car seemed to drive fine. Then, I needed to take it on the highway for a period of time and that's when I realized something was not quite right. The car felt down on power and hesitated accelerating up to speed. The CEL was not flashing so I knew that there was not a misfire. I promptly brought my Volvo to a local auto parts store and had them scan the code. The car threw a P0171 code, a generic code stating that "Bank 1" was reading "too lean".

Bank 1 usually refers to O2 sensors. I had replaced both my O2 sensors last summer so I ruled them out and my thoughts turned to the MAF because as far as I knew, it was original.

The MAF provides information to the ECU so the correct amount of fuel is mixed with a metered amount of air to the engine. It's a very sensitive electronic device that can change idling and acceleration characteristics if it is dirty or failing.

If you think you are experiencing MAF failure you should start by cleaning it. This is what I did and the car was running like it should again!

You will need 

• MAF Sensor Cleaner - DO NOT Use anything else as you may cause damage. No brake cleaner, carb cleaner, degreaser, water, etc. only dedicated MAF cleaner.
• 7mm, 8mm socket or a flat head screwdriver
• T25 Torx Driver

Procedure

Start by disconnecting the MAF connector. Simply push down on the metal release clip and pull it out.

Next, using a 7mm or 8mm socket (if aftermarket clamp is installed), or flathead screwdriver, loosen the hose clamp on the air box side. Slide the hose off of the MAF housing.

Unclip all of the air box housing clips around the perimeter.

You can now move the air box lid from the lower portion of the housing, swing it to the side and gain better access to the T25 screws holding the MAF housing in.

Remove the two T25 screws and wiggle the housing out from the air box lid. It may take a bit of force as there is a rubber o-ring which helps to seal it in place. Do not lose this rubber o-ring if it comes out.

With the MAF out of the air box assembly, you can do one of two things. If you have access to a security torx bit or driver, you can remove the MAF element from its housing completely and clean it that way, however, being 1500 miles from my garage I did not. You can still perform a thorough cleaning without removing the sensor from the housing.

Using the CRC MAF Sensor Cleaner, spray the sensor thoroughly. DO NOT allow anything to touch the sensor. I gave each side about 30 sprays and also cleaned the inside of the housing out as well.

I left mine out of the car for an hour or so to dry completely even though the solution is quick drying. This probably is not necessary but an extra measure you could take.

Reinstall the MAF into the car which is reverse of removal. I also bought a new air filter which I installed as well (something I think I should have done before the trip!).

If you did this process to try and solve a CEL, you can have the code reset with an OBD-II scanner, or, by disconnecting the negative terminal on the battery and leaving it off for about 20min. In any case, if it fixes the problem, the CEL will eventually go away on its own and the MAF sensor can be used without needing to purchase a replacement. In addition to this, you may realize increased fuel mileage and efficiency from your vehicle, saving a bit of money at the pump.

Start your engine up. You may notice a fluctuating idle or an unusually low idle at first, this should go away within a few miles of driving and then it will remain settled. The CEL light will return in 50 or so miles if the MAF requires further diagnosis.

If the problem remains

When a MAF sensor cleaning fails, the part has served its useful life and must be replaced.

94-98 850/S70/V70/C70 Turbo - Volvo Mass Air Flow Sensor - Bosch 0280217107

99+ P80 Turbo - Volvo Mass Air Flow Sensor (S60 S70 S80 V70) - Bosch 8670263

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Written by :

Noah Jenkins

Noah Jenkins is attending the University of Connecticut studying Electrical Engineering. He’s been around Volvos since birth. His knowledge and interest in European vehicles expands to Audi, BMW and Land Rover as well. He currently drives and maintains a 2004 Audi A4 Avant and a 1996 Volvo 850