Limp Mode

[dublina]

I posted this in a reply to a similar problem elsewhere on the forum but I suspect I posted in the wrong place as I didn't receive any response. My apologies if I am duplicating the post.

Anyway I have a problem with a 2015 Mk8 Euro 5 engine with 38K km on the clock. The ACT ( Air Charge Temp ) is reading 45C at startup, despite the ambient temp reading 10C. Once it reaches circa 70C, which happens very quickly, the engine service light comes on and it goes into limp mode. I know that the intercooler is not helping to lower the temperature as the vehicle is stationary, so not sure if this rapid rise in temp is as such normal. Does anyone have any idea of what a normal ACT would be for this engine when the vehicle is idle ?

Additionally I have removed the intercooler ( ACT ) sensor and tested same with an ohm meter. It appears that the sensor is working, as the ohm reading drops when hot air is applied. However without having the factory spec for the sensor, I can't tell whether it's working as designed. I suspect not and propose to purchase a sensor to eliminate this sensor from the equation. In the interim, would anyone know what a normal Ohm reading should be for this sensor ?

I have also checked the pipe work on both sides of the intercooler and all seem to be in good condition i.e. no holes or leaks as far as I can see, so I am pretty sure it's a sensor issue.

Finally could somebody just confirm that there are only two air temp sensors. A sensor just in front of the Air box which I believe is a combination MAF and Intake Air Temp. If I remove the wiring connector I loose the MAF and Intake Air Temp on the live readout so suspect the IAT is part of the MAF. The second sensor appears to be the Air Charge Temp sensor on the outlet side of the intercooler. Is that it or have I missed a sensor somewhere ?

Finally it looks to me that the MAP sensor is on the plastic air intake just below the throttle box housing. Is that correct ?

Any suggestions, photos or info. would be much appreciated. All very difficult without a manual. Seems Haynes have as yet not produced a manual for
the Mk 8.

[Frag]

If the air temp sensor in intercooler does not read same as ambient air temp,(you can check this without even running the van) it's almost certainly faulty.
Alternatively remove sensor from intercooler,leave plugged in hanging free,and compare its temp with ambient.
If not the same fit a new one,fairly common usually logs a MAF code if any.

[dublina]

Hi Frag,

Very much appreciate you taking the time to post a response. Your suggestion makes sense. I will try and revert. Indeed I do have a MAF fault but I don't believe it's where the fault lies because of the high intercooler temp reading.

Am I right in terms of the the location of the second IAT namely that it's built into the MAF ?

Also I saw on another post that a similar fault had been resolved by changing the fuel filter. From your experience is that likely ?

Thanks

[Frag]

The other inlet air temp sensor is incorporated in the MAF,the MAF dtc logged,is due to the volume of airflow,for the given (incorrect) temp after intercooler mismatch....

I'm fairly confident fitting a new sensor with your given description will cure your issue.


Fuel filters,when blocking give a warning message in the message centre on dash cluster,also will log low pressure fuel fault codes.If you have neither of these,changing filter is unlikely to benefit.

[dublina]

Thanks Frag. You really are a fountain of knowledge.
I don't have any fuel filter DTC's so I will discount the fuel filter as a possible source of the fault. I will get a replacement ACT sensor from Ford and see how I get on. I will run resistance test on the new sensor before I fit it and post results for the benefit of anyone else that may have this issue.

Again I very much appreciate your help.

[dublina]

Hi Frag,

Quick post to let you know that it appears that the replacement sensor has resolved the issue. I have yet to take the van for a run to be definitive, but the MAF DTC has not returned after it was cleared and the ACT readout is normal. See screenshot

ACT Print out.jpg

For the benefit of others who may have this fault here is some information.

1. AAT ( Ambient Air Temp ) and ACT ( Air Charge Temp ) should be very close to each other prior to start up. If you look at the screenshot above you will see that they are 5C and 6C respectively. NB. Readings taken after I replaced the ACT sensor.

When I originally looked at the live readout, the ACT was 45C at startup and rose to the high 80's. This causes the ECU to log a MAF fault, due to the readings being outside it's programmed specification, which in turn puts the vehicle into "Limp Mode".

2. As vehicle is stationary during testing, the intercooler will not have air flowing across it to assist in cooling so the ACT will increase the longer the vehicle is left idling. At 2500 RPM I managed to bring it up to 32C but it dropped back to about 12C over the next 5 mins as the engine returned to normal idle speed.

3. The faulty sensor gave an Ohm reading of 3.2K whereas the new working sensor gave a reading of 12.7k. These will obviously vary somewhat depending upon the ambient temp at the time of measurement, but the new sensor reading in this instance, is a good base line.

4. The sensor it located in the intercooler, just behind the front bumper on the passenger side of the engine and is held in place with a rubber "O ring" and T30 Torx screw. See photo below

ACT Intercooler location.jpg

5 Picture of the sensor. Ford Part No. 2 006 019 - Buy genuine from Ford. Cheaper then spurious and you know it will work. It's green in colour.

ACT Sensor.jpg

Thanks again to Frag for his help.

[jimmytb]

Has it worked as I’m having the same problem the van can drive perfect for a few days and go back to your symptoms thanks Jim

[Pompier]

Hi dublina,

I am having the same problem so am picking up a new sensor later today...hopefully...

Just wondering exactly where the sensor is (nearside) and the best way to get to it to replace it.....do you have to remove anything to get at it? Not had time to get under van and look and don't want to remove more than nescessary.

Thanks in anticipation

[Brabbit79]

Hi Gents, im new to the site, I had the same issue. Changed it for new this morning. Do I need to reset as still got the issue. If not any other suggestions on what it could be. Cheers

[k9robert]

hi all
ive got/had the same problem
had it serviced yesterday and dpf cleaned then got this limp mode problem, took out the maf sensor and cleaned it with brake cleaner and drove home last night 130 miles with no problem!
Phoned Ford this morning to order a New Ford MAF sensor and they quoted £260 odd plus vat !!!!
I have a spare air filter cover with a maf sensor in so im going to take it out and carry it round with me to change if the problem with the one I cleaned happens again.
Crazy money from Ford.

Also I need advice on the best HIDs to fit as the light are crap even after fitting Nightsearcher bulbs
hopefully someone can advise me please
cheers guys

[k9robert]

does anyone no the part numbers on the maf sensor, I have two both have all the same numbers but the last four, one says 3H02 and the spare one i have from a 2.2 euro 5 air filter says 4C03 so wondering which is the correct one for my 2014 2.2 euro 5 anyone got any info please.

[tomcox1973]

Some excellent information in this thread... so posting my experience as a nod to those who've helped me by being so explicit.

2015 Mk8 Euro 5 engine with 67k miles on the clock.

Exactly the same symptoms as the OP. In my case the Charge Air Temperature (as it was described in the OBD app I use) was sitting at an implausible 80c with a cold engine and an ambient air temperature of around 20c.

I had originally taken it to some fast fit place. The "technician" read the codes and suggested I returned the following week to have the MAF sensor replaced. It would appear that would have been a complete waste of time and money. I used exactly the part mentioned by the OP, ordered direct from ford for about £16. Very easy to fit.. note it's on the drivers side under front bumper on a RH drive car.

MAF code:
P00BD
Raw code: 00BD
ECU: Engine control unit
Status: Pending
OBDII: Mass air flow (MAF) sensor A - circuit range/performance

Before replacing sensor:

Screenshot_20210826-180818.png

After replacing sensor:

Screenshot_20210826-180849.png

The spikes are when the engine is worked hard. I'm no mechanic but I guess this is to do with the way the turbo works. Even on a drive the temp stays reasonably close to the intake (MAF) temp when not accelerating hard.

[veikkopeikko]

Hello.

I'm trying to solve the same problem (Engine Service Now on the display, reduced power, OBD codes P00BD and P00BC)
Both of these refer to MAF circuit values being too high and too low, accordingly.
Have changed the charge air temp sensor, on the outlet of intercooler, without solving the problem.
Now I have the MAF removed from the airbox pipe and on the desk right now and it has the same kind of tiny element integrated into the MAF (located on the top left corner, if you have it in front of you the same way it sits in its original location).
So, my idea is: should those resistance readings of these two temperature sensors match 100%.
The one on the intercooler pipe gives a reading of 9 kOhms
The one integrated in the MAF gives a reading of 1,91kOhms

Im thinking, if the ECU is comparing these resistance values, shouldn't they be comperable, when surrounding air temp is the same?