S40: 2001 - Mass Air Flow Sensor cleaning fixed problems

[Tom Sawyer]

Re: 2001 Volvo S40 -153,500 miles

For the past two months I have been just sitting in my car, engine RPM 750 and A/C running - while waiting, researching, etc. I did this maybe 5-6 times in two months, 5-15 minutes each time

These codes popped up twice, after clearing previous codes
P 0420 Catalyst System Efficiency - Below Threshhold - Bank 1
P 0102 Mass or Volume Air Flow Circuit Low Input

Issues caused at low speeds or idle
** car shutting off or trying to - I had to keep the RPMs above 1,500 to keep the car running
** poor acceleration, rough running

After a bunch of internet research I tried the easiest solution first =
Clean the MAF Sensor with MAF Sensor cleaner. Very simple task. DO NOT use anything except MAF Sensor cleaner

Boom - Fixed the problems right away. Also - the acceleration and gas mileage seem better, and when shifting into drive it seems the car jumps like it is ready to race.

From my experience, my 21 year old Volvo does not like sitting at idle for more than a few minutes and prefers running at 2,000 plus RPMs

All this just a tip for those with 20+ year old Volvos.
Mine still runs like a champ.

Regards,

Tom

[Tom Sawyer]

Well - I spoke too soon

I've had 32 of these codes in the past 8 months
Cleaning with MAF cleaner helps but not for long

P 0102 Mass or Volume Air Flow Circuit Low Input

--> the codes almost always come in pairs


Anyone have a clue ?
I hate to just start throwing parts at it

[Tom Sawyer]

Greetings -

My Volvo guy replaced all the vacuum hoses + one other and the car ran smoother with better as mileage, but the jury is still out to see if this fixed the "shut off" issue. He checked a couple other things and ONLY charged me $75 - unheard of in my area = city half million people. Takes an hour round trip - but Andy is honest and a gem of a good mechanic !

All three check valves were examined and worked properly.
All connections were tightened or hose clamps replaced.

There are several $200+ parts that are said to be the cause, but I am taking the cheapskate / skin flint / miser / cheap b-terd approach so far.

[Tom Sawyer]

Update 1/08/24

I replaced the following parts trying to solve the Shut-off issue:
***** Volvo Manifold Pressure Sensor - Bosch 9125462
***** Volvo Boost Pressure Solenoid Valve - Pierburg 30670448
***** Volvo Vapor Canister Purge Solenoid - Genuine Volvo 9470775
***** Air Idler Control Valve Genuine Volvo 8670419

All along the OBD reader gave a code for Mass Air Flow Sensor - but research said this part is usually not the problem as they don't often go bad. Even my Volvo mechanic with 20+ years Volvo experience said - probably not the MAF
Well, I must be the exception to the "usual" rule. I replaced the
***** Mass Air Flow Sensor Genuine Volvo 30611532
three months ago and have no issues with "shut-off" since.

Replacing all of the parts helped the car to run better, but only the MAF fixed the shut-off issue. The MAF cost $222 - but it was certainly worth it !