Another Case of Charge Air Intercooler MIL

Hello, everyone. I have searched multiple threads here on the forum without much resolution. I just recently got MIL and VCDS report below. Appears to be an issue with intercooler being non-efficient. It seems to happen sporadically, as while driving today, the after-charge air cooler temperature did not exceed 15 C above ambient temperature. In the MIL report, it appears temperature increased as high as 30+ C which caused MIL to illuminate.

I have had heater core replaced about 30K miles ago with coolant reflushed, but when I inspected coolant, it did turn orange from original pink. I plan to flush the coolant and see if this can resolve the issue.

Wanted to find out if you guys think this may be related to clogged intercooler radiator in front or intercooler square charge pipe. Any suggestions on how I can flush the charge pipe to ensure all contaminants are removed?

Any help would be appreciated!

12642 - Charge Air Cooler
P026A 00 [237] - Efficiency Below Threshold
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 114101 km
Date: 2018.05.01
Time: 21:37:30

Engine speed: 1533.00 /min
Normed load value: 80.4 %
Vehicle speed: 67 km/h
Coolant temperature: 98 °C
Intake air temperature: 58 °C
Ambient air pressure: 1000 mbar
Voltage terminal 30: 13.980 V
Unlearning counter according OBD: 40
Air mass at air mass meter 1: 73.9 kg/h
Temp sensor for low-pressure EGR after cooler: raw value: 103.9 °C
Outside air temperature: 24.0 °C
Intake air temperature before throttle valve: calculated: 35.1 K
Sensor for temp after charge air cooler: raw value: 58.2 °C
Coolant pump for charge-air cooling: spec. value: 95.00 %

Coolant flush was a bust - the MIL came back on despite hours of running hose water through intercooler and its own radiator.

Hoping someone can suggest how to diagnose whether the issue lies in the intercooler radiator that is in front of main radiator or if it is the actual charge air intercooler (square pipe) that is at fault. Anyone disassemble the charge air intercooler - is it worth taking apart and making sure it is not simply contaminated where turbocharged air flows? Does it contain similar honeycomb veining as the radiator itself?

The coolant I drained was orange with a multitude of black and orange specs - clearly broken down. Hopefully it has not clogged heater core again, will see this winter.

Any help appreciated.

eugene,

my experience w this code has been that the fault is in the sensor and/or its wiring harness connector not in the charge air cooling system components.

i have cleared this code by replacing the combination MAP/IAT sensor (and/or repairing its wiring harness connector).

you should find it as item 3 in the CKRA charge air cooling dwg at this link:
https://nemigaparts.com/cat_spares/etka/volkswagen/pa/691u/145900/

VAG p/n 03G906051E
BOSCH 0281002976

i don't know how to test this sensor (but i've cleared this code twice on my rig by replacing it). if you go this route shop for the best price for the sensor. i've found that prices vary widely for this item. i've paid as low as $30 using the Bosch p/n online while my local dealer wanted >$100.

also, i used the pins from one of the faulty sensors i replaced to do a "pin drag" test on the wire harness connector to find that the female terminals in the connector needed to be replaced (found them at Mouser Electronics for $0.70/each).

sorry you had this problem. good luck getting it worked out!

bob.

flyboybob said:

eugene,

my experience w this code has been that the fault is in the sensor and/or its wiring harness connector not in the charge air cooling system components.

i have cleared this code by replacing the combination MAP/IAT sensor (and/or repairing its wiring harness connector).

you should find it as item 3 in the CKRA charge air cooling dwg at this link:
https://nemigaparts.com/cat_spares/etka/volkswagen/pa/691u/145900/

VAG p/n 03G906051E
BOSCH 0281002976

i don't know how to test this sensor (but i've cleared this code twice on my rig by replacing it). if you go this route shop for the best price for the sensor. i've found that prices vary widely for this item. i've paid as low as $30 using the Bosch p/n online while my local dealer wanted >$100.

also, i used the pins from one of the faulty sensors i replaced to do a "pin drag" test on the wire harness connector to find that the female terminals in the connector needed to be replaced (found them at Mouser Electronics for $0.70/each).

sorry you had this problem. good luck getting it worked out!

bob.

Click to expand...

Thank you so much for your expedient reply. I saw the Bosch item on Amazon for $32 - will try that next to see if it fixes the issue. Much better than breaking down $250 for a new charge air intercooler which may not be the issue at all. Will post back with the results. This is the first MIL I have had on this car since warranty expired. Glad I still replaced the antifreeze since old one was clearly bad in hopes this will avoid future radiator/heater core plugs. I am surprised how much fine sediment came out when I flushed it and lo-and-behold, I see some more dark sediment in coolant expansion reservoir after driving with new coolant. Afraid another drain and replace will be in order. Wondering if non-VW antifreeze will be less likely to break down...but scared to try in case it breaks something else.

eugene,

i have been using

Pentosin Pentofrost E (mixed 50/50 w de-ionized or distilled water)

antifreeze for over 100k miles without problems (no heater core issues so far @ 160K miles).

here is a spec sheet link:

http://www.pentosin.net/specsheets/Pentofrost_E.pdf

i have found some rust sediment during/after coolant flushes too. i believe some of that is to be expected (in a water cooled iron block engine) and have never worried bout it much.

there are some good threads here about easy methods to do the coolant flush (shop vac method is one). advanced search is your friend.

bob.

For note, on the highway, that coolant should get heat soaked pretty good. I was monitoring CAIT over 600 miles of highway runs recently and it stayed about 2-50F higher than coolant temp, so 210-250F on highway with peak of over 300 during regens and hill climbs.

This was observed on our '15 Passat last week via Torque. granted the tamps fell pretty quickly during coasting but still climbed just as fast once back on it.

Check out this thread. I included a couple pictures. the sensor samples the air inside the intercooler, not the coolant. The sensor gets fouled up, and the control system can't correctly interpret the values received.

http://forums.tdiclub.com/showthread.php?t=474635

I'll remember that, wonder if it still applies to Gen3s.

We had zero codes for our 2012 over the 80K we had her.

The sensor replacement was a success! Appreciate everyone's input and help. Of note, as I was clearing codes, a new code P0111 for bad sensor was stored with the original code. I cleared both after replacing sensor and so far none have appeared.

The faulty sensor was covered with a small amount of oil. Is this oil coming from the turbo? Is it normal to see some oil or is turbo on its last leg? Nothing is making any strange sounds as I would expect from dying turbo. Thank you all so much for the help. This was a $32 fix.

eugene,

glad you got this sorted out.

my experience is that the turbocharger compressor seals on my 2012 tdi se leak oil into the intake at the rate of about 1/2 to 1 pint (250 to 500 ml) per 10,000 miles (i.e. between oil changes). i believe this is due in part to my driving style (more often off the go pedal than on it) and to the fact that my turbo compressor blades show evidence of FOD (borescope inspection shows compressor blade leading edge damage most likely due to ingestion of foreign objects).

i believe it's easy to check if the turbo compressor oil seals are letting oil into the intake. i just remove the hose elbow at bottom of (entrance to) the intercooler. i find most of the leaked oil collects in the bottom of the intercooler. i clean it out regularly now (about every 25K miles). seems cheaper/easier than replacing the turbo.

maybe knowin this won't help you to sleep better at night but i've learned to drive more and worry less. hope that helps.

bob.

eugene89us said:

The sensor replacement was a success! Appreciate everyone's input and help. Of note, as I was clearing codes, a new code P0111 for bad sensor was stored with the original code. I cleared both after replacing sensor and so far none have appeared.
The faulty sensor was covered with a small amount of oil. Is this oil coming from the turbo? Is it normal to see some oil or is turbo on its last leg? Nothing is making any strange sounds as I would expect from dying turbo. Thank you all so much for the help. This was a $32 fix.

Click to expand...

Score for a $32 fix! dealer would have changed the hoses, the IC, done flushes and set you back a good $1500.

Oily residue is most likely EGR gunk, while USLD has helped with egr build up EGR duty cycles have increased. This goop is the new form of the black carbon build up seen on mk4s.

flyboybob said:

eugene,
glad you got this sorted out.
my experience is that the turbocharger compressor seals on my 2012 tdi se leak oil into the intake at the rate of about 1/2 to 1 pint (250 to 500 ml) per 10,000 miles (i.e. between oil changes). i believe this is due in part to my driving style (more often off the go pedal than on it) and to the fact that my turbo compressor blades show evidence of FOD (borescope inspection shows compressor blade leading edge damage most likely due to ingestion of foreign objects).
i believe it's easy to check if the turbo compressor oil seals are letting oil into the intake. i just remove the hose elbow at bottom of (entrance to) the intercooler. i find most of the leaked oil collects in the bottom of the intercooler. i clean it out regularly now (about every 25K miles). seems cheaper/easier than replacing the turbo.
maybe knowin this won't help you to sleep better at night but i've learned to drive more and worry less. hope that helps.
bob.

Click to expand...

There were some '12 with a TSB/warranty extension for bad turbos.

We had 80K trouble free miles on our '12, never had to top up the oil, never a CEL.