Thread: Restricted Performance and GAP IIDTool Faults

MOST bus is the audio system

Ok, so the MOST is associated with the audio system. From what I have read in the GAP Tool manual, U faults are generally able to be cleared and ignored unless persistent. I've still got the restricted performance and red warning light up on the dash display, but no other ECU faults. That seems to be illogical to me.

PXL_20211214_030141786.NIGHT[1].jpg

in the the advanced settings of the faults - add in pending faults and see what pops up.

OK. So Christmas has intervened in my diagnostic efforts. My D4 battery was getting low so I charged it up and noted that the Restricted Performance and RED waring light was still up with ignition on.
Now the GAP Tool was telling me:

PCM - Engine Diesel 3.0 L HSCAN - 1 fault

P010D-00 (AF) Mass or volume air flow B-circuit high
At 202656 14-12-2021

So I thought that if I swapped the MAF sensors and the fault goes to A then it is a faulty B sensor. Easy. Not so easy... With a bit of fiddling with the looms, I managed to swap the connectors. I noticed that the forward sensor incorporated a temperature sensor. So any fault there could be ignored.

After swapping the sensor connectors, started the engine and got No Faults on the GAP Tool. So I swapped the connectors back and went for a drive around the block (about 5 minutes). The Restricted Performance was no longer showing, but the Red Warning indicator was still on and the engine felt sluggish (like no turbos).

I remembered to re-read this thread and on the GAP went for Advanced faults pending and got the following:

PCM - Engine Diesel 3.0 L

P010B-22 (64) Mass or volume air flow B circuit - range/performance - General Signal failure - signal amplitude&gt: maximum
At 202659 km
Triggered on 09-01-2022 14:47:26

P010D-00 (27) Mass or volume air flow B - circuit high
At 202659 km
Triggered on 09-01-2022 13:44:34

I can't see any oil escaping from the engine, so it is unlikely to be a manifold (the RH manifold was replaced not long ago). Can it be a faulty MAF sensor or is there more investigating to be done?

Originally Posted by StewG

OK. So Christmas has intervened in my diagnostic efforts. My D4 battery was getting low so I charged it up and noted that the Restricted Performance and RED waring light was still up with ignition on.
Now the GAP Tool was telling me:

PCM - Engine Diesel 3.0 L HSCAN - 1 fault

P010D-00 (AF) Mass or volume air flow B-circuit high
At 202656 14-12-2021

So I thought that if I swapped the MAF sensors and the fault goes to A then it is a faulty B sensor. Easy. Not so easy... With a bit of fiddling with the looms, I managed to swap the connectors. I noticed that the forward sensor incorporated a temperature sensor. So any fault there could be ignored.

After swapping the sensor connectors, started the engine and got No Faults on the GAP Tool. So I swapped the connectors back and went for a drive around the block (about 5 minutes). The Restricted Performance was no longer showing, but the Red Warning indicator was still on and the engine felt sluggish (like no turbos).

I remembered to re-read this thread and on the GAP went for Advanced faults pending and got the following:

PCM - Engine Diesel 3.0 L

P010B-22 (64) Mass or volume air flow B circuit - range/performance - General Signal failure - signal amplitude&gt: maximum
At 202659 km
Triggered on 09-01-2022 14:47:26

P010D-00 (27) Mass or volume air flow B - circuit high
At 202659 km
Triggered on 09-01-2022 13:44:34

I can't see any oil escaping from the engine, so it is unlikely to be a manifold (the RH manifold was replaced not long ago). Can it be a faulty MAF sensor or is there more investigating to be done?

Have you enabled Pending Faults under advanced? I would expect to see a P006a fault with that which is a volumetric mismatch between MAF and MAP. I say this based on you swapping the MAF and still it says the B sensor. I had this two, I swapped MAF, was still there, then found the pending fault. It was an intake leak.

Originally Posted by DiscoJeffster

Have you enabled Pending Faults under advanced? I would expect to see a P006a fault with that which is a volumetric mismatch between MAF and MAP. I say this based on you swapping the MAF and still it says the B sensor. I had this two, I swapped MAF, was still there, then found the pending fault. It was an intake leak.

I did enable the Advanced > Pending faults, but I had already swapped the sensors back. I'm going to have to do the whole exercise again to see if B fault changes to A fault.

Apart from two trips around the block, I've barely driven the car in many months and both the D4 and my caravan are a spiders' paradise - covered in cobwebs...

Originally Posted by StewG

I did enable the Advanced > Pending faults, but I had already swapped the sensors back. I'm going to have to do the whole exercise again to see if B fault changes to A fault.

Apart from two trips around the block, I've barely driven the car in many months and both the D4 and my caravan are a spiders' paradise - covered in cobwebs...

It may be the MAF then. Swap them, then see if the fault goes until the second turbo kicks in. After that, if confirmed, try a MAF cleaner before you buy a new one.

Over the past few days, I have been fiddling with the MAF sensors, including cleaning with CRC MAF Sensor Cleaner (it made no difference). The attached pdf (if I get it attached ) shows GAP Tool screen shots and explanations. I'm still at a loss to know exactly what the problem is although I have seen a small amount of oil on the LH intake manifold and hope that it is not cracked. The RH side was replaced about two years ago when I first got "Restricted Performance" and that set me back about $1600.