mileage has become progressively worse, could it be related to P2015-003 code

Hi everyone. Thanks for reading. My 2011 TDI Golf 6 speed manual just clocked 80,000 miles. I did the VW emissions retrofit exactly one year ago. I immediately noticed that my actual mpg was about 2.5 mpg less than the MFI system was estimating (my actual mpg and the MFI used to correspond closely before the VW emissions retrofit). In consideration of the VW restitution, I was totally fine with the disparity.

Going into the fall, my yellow "check engine/engine malfunction" light came on a few times, but the light would usually go back off in a day or two. But last winter the light came on and stayed on. I took it the shop I have been trusting to do my service, and the tech told me that it was a sticking intake manifold flap position sensor. He told me that it was a common issue with these cars, but the technician told me that I was not hurting the car to continue to run as is for now.

008213 - Intake Manifold Flap Position Sensor (Bank 1) P2015 - 003 Implausible Signal - MIL ON

My mileage has been poor, but it has been cold in Ohio until just recently.

I just took a 1500 mile trip south, and my MFI was indicating the kind of mileage I expected (42 - 45 mpg), but when I got home and updated my Fuelly log, I was shocked to see that my actual mileage was now about 9 mpg below the MFI estimates.

The engine seems to run fine, but I am noticing more regen type activity.

At this point, I feel that I should take it to the dealership (I bought the car new) and get their input. Could this be covered by warranty? My repair shop told me that they can make the repair to the manifold intake flap for about $300. Could my poor mileage be related to the intake manifold?

Any advice is appreciated.

Thanks

Could partially be the effect of winter fuel; also, when was your last fuel filter change? Mileage drop due to progressively clogging filter, maybe? Tires kept at correct psi?

This part was installed on my mom's 2011 with good results: https://www.dieselgeek.com/products...-rail-tdi-with-aluminum-manifold-03l-129-711e

However, since you've had the emissions fix completed, I would expect VW would cover it in full under the emissions warranty. Call your dealer and ask.

VW will give you a new manifold. I got one. Just go get it fixed. And yes, there is more regen activity after the fix, the mpg is worse after the fix, and the mpg is also worse in cold weather.

Thanks Ksing. I did call the dealer today before seeing your post. The service rep at Byers VW in Columbus told me that there is a $120 diagnosis fee, but he also told me that I won't have to pay the fee if the repair is covered by warranty. So thanks for telling me what I can hope for.

As for the large drop in fuel efficiency, I hope that it will be corrected with the manifold repair. As I said, I got the emissions retrofit work done a year ago, and my mileage only declined about 7% afterward, but lately my mpg is alarmingly bad. My MFI during the last 4 highway driving tanks was estimating about 43 mpg, but my actual was 34 (and this was while driving in warm weather with no A/C running).

catfish_hunter said:

My MFI during the last 4 highway driving tanks was estimating about 43 mpg, but my actual was 34 (and this was while driving in warm weather with no A/C running).

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Interestingly, my Fuelly report indicates my car averaged 33.8 mpg over my last 10 tanks. Just like you!

The fix definitely affected my mpg, but even more my mpg is affected by the kind of trips, e.g., cruising the highway day after day as a commuter vs. making shorter trips around home. My commute changed from 5-days per week to only Tuesdays and Thursdays, so I have more short trips as a proportion of my driving and my historical average is sinking. I don't think you should worry so much.

For the diagnosis fee, I always take a printout of the portion of my VCDS scan with the code(s) and a Googled explanation of exactly what that code indicates is wrong with the car and how to fix it. They still say something about diagnosis charges, but it never comes to pass becuase it's exactly what I said and they just fix the car.

Dealer serviced my car today. Intake manifold was replaced. Warranty covered everything. The service tech told me that the manifold issue would cause poor fuel mileage.

Labor notes:
"Faulty intake manifold runner position sensor. Connected battery charger and scan tool. Performed GFF scan. Fault codes P2015 intake manifold runner position sensor/switch circuit range/performance mechanical malfunction static, P2008 intake manifold runner bank 1 control circuit/ open intermittent. Performed populated test plan for checking intake manifold flap motor. Checked reference voltage and found to be good at 4.99 volts. Checked wiring and found no loose or damaged connections. Test plan indicated faulty intake manifold. Loosened wiring harness, R and R charge air pipe, throttle valve, EGR valve, high pressure fuel supply line. Loosened and moved coolant lines,. Removed and replaced intake manifold and required gaskets. Fault codes. Road Tested vehicle to verify repair and that check engine light remains off"

Great news! Good luck with your car!