2007 XC70 ECM121B code when below freezing, 30711554 Topic is solved

XC70Rider · Post by **XC70Rider** » 22 Nov 2018, 19:08

When I first got the XC70 last May OBDII code P0101 would come up every other week only during cold starts. She idles nice and smooth and has no hesitation so I didn't predict the MAF was defective. After getting VIDA last month I narrowed it down to ECM121B.

Here's a list of work performed so far to solve this code:

>New Vacuum hoses and new clamps
>New Bosch MAF
>New fuel filter
>BG44K fuel injector cleaner
>Cleaned ETM and installed with new gasket

The PCV system was replaced before purchase but there was still crud on the intercooler rubber hoses and ETM intake pipe. With the crud on the intake pipe I thought the throttle was never cleaned so I dropped the ETM. There was no carbon on butterfly valve so I just gave it another cleaning and reinstalled with a new gasket. I have checked for vacuum leaks by spraying carb cleaner around hoses and gaskets during engine idling but got no RPM change.

Now that it's below freezing outside the ECM121B code appears during every start with either a cold or warm engine. I predict the rubber intercooler hoses or the intake manifold gasket is causing the leak by not expanding in freezing weather?

Your assistance is appreciated.

Post by **precopster** » 23 Nov 2018, 01:28

What is MAF flow at idle in KG/Hr? You should be able to see this in Vida. Is air filter replaced/clean?

Possible source according to a Vida search:

• 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.

XC70Rider · Post by **XC70Rider** » 23 Nov 2018, 07:38

precopster wrote: ↑23 Nov 2018, 01:28 What is MAF flow at idle in KG/Hr? You should be able to see this in Vida. Is air filter replaced/clean?

Possible source according to a Vida search:

• 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.

I installed a new air filter on the first day of purchase back in May. A week later I also gave the air box a scrubbing since I had to pop it out to replace the burnt vacuum pump. I cleaned the MAF connector and the pigtail connector using electrical spray cleaner when I installed the new Bosch MAF.

The MAF flow is 9.9 kg/h when idling

The ECM does an Air Mass correction of 0.85.

XC70Rider · Post by **XC70Rider** » 23 Nov 2018, 07:53

When using my OBDII smartphone APP it reads 3% lean during startup. After warming up during the drive it increases up to 7% lean. Around then is when the ECM-121B will appear. It will go into limp mode and get a good mixture starting at 0%. During the frigid temperature yesterday of 10F (-12.2C) after it went into limp mode it would still run lean at 7%.

The solo used car dealer I got her from did the PCV cleaning himself. The rubber hose connected from the oil trap to block isn't clamped down securely. I can rotate the crimped clamp on the block side by hand and it causes a minor oil leak. The long hose connected from oil trap to PTC had a zip tie on the PTC end! When replacing the zip tie with a metal clamp I found no cracks in that hose and the PTC was cleaned. The intake manifold gasket does appear to be new so he replaced that while doing the PCV cleaning.

Could a loose hose on the oil trap cause a Lack of Air Flow? My next step appears to be removing the intake manifold and inspecting the oil trap hoses. To proceed all I need is the dipstick o-ring I can get at the Volvo dealer 20 miles north. Already have the gaskets, banjo bolt, crush washers, fuel injector o-rings, hoses and such.

Post by **precopster** » 24 Nov 2018, 00:03

That's low. There is a loose hose there somewhere. Should be between 12.5KG/hr and 14kg/hr

The hose that always catches people out is the one on the ETA. It can get a crimp from the clamp quite easily due to the lack of vision when refitting it.

I always remove the air cleaner box totally and inspect the way it refits by poking my head down into the vacant space left by the airbox

XC70Rider · Post by **XC70Rider** » 24 Nov 2018, 07:53

I removed and inspected both intercooler pipes yesterday. I found no cracks on the rubber hoses. Both ends fit tight onto the intercooler and turbo. The plastic pipe to the ETM appeared to have no cracks nor bends. Both ends fit tight on the intercooler and the ETM.

If that pipe was crimped would it cause a major leak with backfiring? It appeared to fit well when I held it up with one hand and tightened the clamp with a 7mm socket using the other hand. Using my borescope I'll give it a check this morning.

I was able to remove that fat PCV elbow hose connected to the block. I used good quality worm clamps to get both ends connected. Neither end of the hose nor it's clamps can move now. There was no crud on the block port so it was cleaned when PCV oil trap was replaced. I'll see if it fixes that oil leak. All other PCV hoses were tight and I couldn't rotate the hoses nor their clamps.

Here are the 3 last culprits I suspect could be causing the minor air loss:

1. The O-ring on the MAP sensor connected to the intercooler might be dried up and cracked.

2. The ETM plastic pipe could be crimped.

3. The banjo bolt connected to the intake manifold. I don't know if new crush washers were used when the PCV was cleaned up before I got her. I did spray carb cleaner around the banjo bolt with the engine idling but got no RPM change. I had a cloth covering the alternator. I'll try it again this morning.

XC70Rider · Post by **XC70Rider** » 24 Nov 2018, 21:19

I removed and inspected the plastic intercooler pipe connected to the ETM.

The ETM hookup end looks smooth with no crimp markings. I inserted it back tight and snug onto the ETM.

The MAP sensor O-ring looked fine with no cracking.

I sprayed the sensor with MAF cleaner and applied a touch of silicone grease around the O-ring. The grease will give it a nice fit and keep it from cracking.

I also sprayed CARB cleaner around the banjo bolt and several other intake areas again and got no RPM change.

Well it was neither that pipe nor the MAP sensor. I took her for a ride this morning at 26F (-3.3C) and she still ran lean with the ECM-121B code appearing within 2 miles.

XC70Rider · Post by **XC70Rider** » 24 Nov 2018, 21:31

An hour later I removed the intercooler pipe connected to the turbo. For the first time I loosened the clamps between that plastic pipe and it's rubber hoses and removed only the plastic pipe. I re-installed that plastic intercooler pipe tight and snug.

Another thing I gave a shot is further tightening the top 3 and bottom 2 intake manifold mounting bolts. I couldn't reach the bolt hiding behind the thermostat.

I then took her for a ride when it was 40F (4.44C) outside and the code didn't come back. The long term Fuel Ratio also dropped from 5% down to 0%!

I hooked up VIDA and the ECM-121B code didn't appear. It was either the intercooler pipe rubber hose leaking or the intake manifold gasket I tightened wasn't replaced when the PCV was cleaned before I got her? Another culprit might be the cold dry air knows how to find those tiny leaks?

I'll remove the intake manifold and clean things up when I have time. Just need to purchase a wrench that can reach the bolt behind the thermostat housing.

Post by **abscate** » 25 Nov 2018, 02:59

You can get to that hidden on with a 1/4 drive ratchet and M6 socket on a long extension and a wobble. Not too tight,like firm wrist torque, not elbow torque

I'm cruising MA on Tuesday if you want a stop in by the Merry MVS mechanic...pm me

XC70Rider · Post by **XC70Rider** » 25 Nov 2018, 07:28

abscate wrote: ↑25 Nov 2018, 02:59 You can get to that hidden on with a 1/4 drive ratchet and M6 socket on a long extension and a wobble. Not too tight,like firm wrist torque, not elbow torque

I'm cruising MA on Tuesday if you want a stop in by the Merry MVS mechanic...pm me

I tried reaching it with a 3/8" extension with a wobble joint on a 10mm socket but it was too tight. I have 1/4" extensions but am missing the 1/4" wobble joint. I'm going to Harbor Freight today to purchase the Serpentine Belt Tool Kit so I'll see if they have this universal socket set in stock

https://www.harborfreight.com/3-pc-univ ... 67986.html

Thanks for the tip and offer for assistance! If it doesn't work then I'll send a PM.