P0101 in cold weather only

hu5ker555 · Post by **hu5ker555** » 05 Dec 2017, 06:06

2005 S80 2.5T, 180K

For the second year in a row, as winter sets in I get a P0101. Engine runs fine, no other symptoms. I've cleaned the MAF and filter.
I'm wondering if it's possible that there is a very minor vacuum leak somewhere, which appears in cold weather when the rubber/plastic contracts. Any ideas/suggestions?

Post by **Roger_850T** » 10 Dec 2017, 20:09

It would be helpful if you had VIDA, as the generic P0101 can be either Volvo's "ECM-1210 Mas air flow (MAF) sensor - Flow Too High" or ECM-121B Mass air flow (MAF) sensor - Flow too low".

In both cases, the ECM calculates how much the airflow ought to be, then it sets the code if the actual measured flow is outside of that amount +/- a range.

From VIDA, in both cases, possible causes are:
- Contact resistance or oxidation in the mass air flow (MAF) connectors
- Air leakage in the intake system
- Blocked intake system
- Damaged mass air flow (MAF) sensor.

So, looking for vacuum leaks is a good start.

Roger

hu5ker555 · Post by **hu5ker555** » 10 Dec 2017, 20:18

Thanks, Roger. So I should try spraying carb cleaner around the intake and see if it revs up? Any particular locations or other suggestions?

Post by **Roger_850T** » 10 Dec 2017, 20:31

I would look in two places. First, some of the big air hoses can fail, especially if you have a lot of miles and your turbo is leaking some oil into the intake system. I would feel all around them, and check that they feel firm (not squishy) and don't have any tears or holes.
Second, I would check out the little vacuum elbows. I'm not sure exactly where they are on your engine, but they can get soft and fail, also, and cause issues.

I'm trying to think why it would only give you the error code when the outside air gets colder. Maybe it's as you said, a hose getting stiffer with the cold and not sealing as well. Nothing else extraordinary comes to mind - I'll let you know if I think of anything.

Roger

Post by **RickHaleParker** » 10 Dec 2017, 21:41

"I'm wondering if it's possible that there is a very minor vacuum leak somewhere, which appears in cold weather when the rubber/plastic contracts. Any ideas/suggestions?"

Marginal leak in the intake manifold gasket that is only sufficient when the gasket is cold ... metal contracts when cold.

When the engine is stone cold, fire it up and spray burst of starting fluid around the intake manifold gasket. If there is a leak, it will suck in the starting fluid and your hear the engine surge.

Post by **mrbrian200** » 10 Dec 2017, 22:27

I would also put the throttle body on the suspect list. The internal nylon gears could possibly be worn. In my experience with this type of failure it acts up in cold weather and will set DTCs for the MAF. The ECU seems to ignore the TPS which indicates a part open throttle plate that isn't returning fully to the idle position, or sticking at certain points and not allowing the throttle plate to open as much as the ECU commands. But it does set DTCs for incorrect air flow through the MAF under these conditions.

However, you do want to thoroughly rule out intake leaks and the sensor/wiring before looking into this if you haven't already.

Post by **Skymongrel** » 26 Nov 2021, 08:24

So my 2006 XC70 is doing this exact same thing! In fact this is the third year that I've had it pop up during a cold snap. It usually goes away. Sure would like to solve it once and for all. I've read some good tips here but was wondering if you ever resolved your problem?

Thanks for any help you can offer. BTW I was taking the car in to get inspected and this P0101 popped up!! Can't win.

Post by **xHeart** » 27 Nov 2021, 08:29

RickHaleParker wrote: ↑10 Dec 2017, 21:41 "I'm wondering if it's possible that there is a very minor vacuum leak somewhere, which appears in cold weather when the rubber/plastic contracts. Any ideas/suggestions?"

Marginal leak in the intake manifold gasket that is only sufficient when the gasket is cold ... metal contracts when cold.

When the engine is stone cold, fire it up and spray burst of starting fluid around the intake manifold gasket. If there is a leak, it will suck in the starting fluid and your hear the engine surge.

RHP, is there a sensor associated with reporting P0101?

Post by **RickHaleParker** » 27 Nov 2021, 10:02

xHeart wrote: ↑27 Nov 2021, 08:29 RHP, is there a sensor associated with reporting P0101?

P0101 is based on calculated air flow vs measured air flow from the Mass Air Flow Sensor when the long term fuel trim is above or below a set value.