P0096

[bramborne]

Hi all.
After some advice on trouble code P0096 on a 2016 A180d 1.5d.
Have read through the various posts but I can't find a definitive answer to the problem.

So code reader indicates IAT2 at being at fault. Looking at live data I see that the IAT (no option to see IAT2) is sat at 90 degrees C. And does not move.

I removed the MAF with integrated IAT and did some resistance checks. Now, I'm not sure what pins are which but between pins 3 and 4 I got a reading of between 2.4 and 2.6 kohms. When looking at data for an IAT, this world seem to equate to 90 degrees.

Now the question is, does anybody know if these 2 pins are actually the IAT connections or is it just coincidence that the resistance I am seeing would equate to the IAT showing 90 degrees.

Another thing is if I unplug the MAF, new codes are produced to say problems with MAF and IAT2. Plug it back in and clear faults and there are gone. This leads me to believe that this sensor is actually IAT2.

That said, when unplugging the sensor, I expected a change to the indicated temp but it did not move from 90. This now suggests that it's not the IAT2 sensor.

Can anyone shed any light onto this issue. I don't want to buy a new MAF/IAT if there is a chance that is not the right call. I'm thinking that I will have to go to a specialist at some point but would like to have a go at fixing myself.

Another thread said that he had used a specialist and they had changed the MAP to cure the fault but I'm not sure how the two are related.

Thanks for your time.

 

[bramborne]

Hi all.
After some advice on trouble code P0096 on a 2016 A180d 1.5d.
Have read through the various posts but I can't find a definitive answer to the problem.

So code reader indicates IAT2 at being at fault. Looking at live data I see that the IAT (no option to see IAT2) is sat at 90 degrees C. And does not move.

I removed the MAF with integrated IAT and did some resistance checks. Now, I'm not sure what pins are which but between pins 3 and 4 I got a reading of between 2.4 and 2.6 kohms. When looking at data for an IAT, this world seem to equate to 90 degrees.

Now the question is, does anybody know if these 2 pins are actually the IAT connections or is it just coincidence that the resistance I am seeing would equate to the IAT showing 90 degrees.

Another thing is if I unplug the MAF, new codes are produced to say problems with MAF and IAT2. Plug it back in and clear faults and there are gone. This leads me to believe that this sensor is actually IAT2.

That said, when unplugging the sensor, I expected a change to the indicated temp but it did not move from 90. This now suggests that it's not the IAT2 sensor.

Can anyone shed any light onto this issue. I don't want to buy a new MAF/IAT if there is a chance that is not the right call. I'm thinking that I will have to go to a specialist at some point but would like to have a go at fixing myself.

Another thread said that he had used a specialist and they had changed the MAP to cure the fault but I'm not sure how the two are related.

Thanks for your time.

Further to my last. The plug on the MAF has only 4 pins. How can that provide enough connections for both MAF and IAT?

 

[mattkh]

Mileage please and
Engine type code

 

[supernoodle]

Not familiar with that engine in the Merc, but can give some general pointers.

Air pressure/temp sensors are numbered from the free end, starting 1 at intake going up in index as you go upstream. Exhaust are numbered 1 closet to engine and go up in index as you do downstream.

So I would normally expect IAT1 to be MAF and IAT2 to be a charge air temp(note this could be a TMAP, which would fit with why you read some had changed the MAP).

If unsure, disconnecting the components and seeing what other DTCs you get is a good way of confirming component. I see you already did this. I would extend this to disconnecting the charge air temp and see what it says. Note when you've disconnected the correct sensor you should see a corresponding IAT2 circuit high, not just a range/performance.

The 90deg is implausible for an air temp, so guessing it's a replacement value.

With a 4 wire MAF it's possible to have a power, MAF signal, temp signal and a common ground. Same with a TMAP, that's power, pressure signal, temp signal and ground.

Temp sensors are nothing more than variable resistors. The ECU pin is internally pulled up to 5v, the sensor being connected between the pin and ground forms a potential divider. So to simulate a sensor for testing you can just connect a variable resistor.

 

[bramborne]

Many thanks for your reply. I will go and have another look and disconnect some more sensors and see if I get a change a change fault code as you suggest (if it stops raining). Only concern was when I disconnected the MAF it came up with a code for IAT2. Will check that again though. Trouble is it's my son's car and he's only back at weekends.

Again, thanks for taking the time to reply.

 

[ajlsl600]

Not familiar with that engine in the Merc, but can give some general pointers.

Air pressure/temp sensors are numbered from the free end, starting 1 at intake going up in index as you go upstream. Exhaust are numbered 1 closet to engine and go up in index as you do downstream.

So I would normally expect IAT1 to be MAF and IAT2 to be a charge air temp(note this could be a TMAP, which would fit with why you read some had changed the MAP).

If unsure, disconnecting the components and seeing what other DTCs you get is a good way of confirming component. I see you already did this. I would extend this to disconnecting the charge air temp and see what it says. Note when you've disconnected the correct sensor you should see a corresponding IAT2 circuit high, not just a range/performance.

The 90deg is implausible for an air temp, so guessing it's a replacement value.

With a 4 wire MAF it's possible to have a power, MAF signal, temp signal and a common ground. Same with a TMAP, that's power, pressure signal, temp signal and ground.

Temp sensors are nothing more than variable resistors. The ECU pin is internally pulled up to 5v, the sensor being connected between the pin and ground forms a potential divider. So to simulate a sensor for testing you can just connect a variable resistor.

Very interesting, I often use a resistor to provide an in range reading for a speed sensor that has failed and I don't have a replacement and I need to calibrate clutch fills. It works.

 

[bramborne]

Eventually found the MAP sensor. Interestingly, when disconnecting the plug the IAT dropped from 90 degrees C to 0 degrees C. When reconnecting, it shot back up to 90 degrees so this is looking more likely to be the problem sensor.

 

[bramborne]

Just info for anyone with the same issue. It was the MAP sensor which is partly under the EGR valve. Very poor design as have to remove EGR to get the sensor retaining bolt out. What should be a 10 min job turned into over an hour's work.

The key to finding this fault was to look at the IAT in live data on code reader. Mine was reading 90 degrees but when unplugging the sensor this fell to 0 degrees. I slaved in the new sensor before removing the old one and the live data registered 15 degrees.

Upon removing the old sensor, it was very dirty so that could have been the issue. However, I was passed the point of no return to remove so just fitted new sensor instead.( Having removed the EGR valve)

Started the car and noticed a shift in engine note. Not my car so just could do that normally bit I like to think that it adjusted the mixture to run smoother.

Obviously my checks on the MAF could have been a right wild goose chase but with some appreciated ideas from Supernoodle I got there in the end.

Part was from ECP at £38. Probably could have got cheaper but it's Sunday so limited choice.

Hope this helps someone in the future and a thanks to Rizzy123 for pointing me in the direction of the MAP sensor.

 

[Blobcat]

Good/great forum this

 

[ajlsl600]

Just info for anyone with the same issue. It was the MAP sensor which is partly under the EGR valve. Very poor design as have to remove EGR to get the sensor retaining bolt out. What should be a 10 min job turned into over an hour's work.

The key to finding this fault was to look at the IAT in live data on code reader. Mine was reading 90 degrees but when unplugging the sensor this fell to 0 degrees. I slaved in the new sensor before removing the old one and the live data registered 15 degrees.

Upon removing the old sensor, it was very dirty so that could have been the issue. However, I was passed the point of no return to remove so just fitted new sensor instead.( Having removed the EGR valve)

Started the car and noticed a shift in engine note. Not my car so just could do that normally bit I like to think that it adjusted the mixture to run smoother.

Obviously my checks on the MAF could have been a right wild goose chase but with some appreciated ideas from Supernoodle I got there in the end.

Part was from ECP at £38. Probably could have got cheaper but it's Sunday so limited choice.

Hope this helps someone in the future and a thanks to Rizzy123 for pointing me in the direction of the MAP sensor.

Always love to read a wriggle, well dun.