Hi,

I have a problem with my Discovery 2 TD5. The air mass sensor is not giving any values. After evaluating the problem I noticed that there are no values ​​in the MAF. The pin 1 and 2 o 3 (12v) have no connection problem, the cabling is good. I made the following test to evaluate the cabling. I measured the continuity of the two pins to ECU pin 11 and 20. The continuity is assured, validated if the other wiring pins have continuity to see the signal pass to them and have a cable problem, and all seems okay.

Then I evaluated the behavior of MAF. What I found was, when I have only the ignition on the 12v are correct and the others 2 pins have the right residual values, I assessed the continuity of MAF pin 1 to the mass and was guaranteed. After putting the car to work, pins 1 and 2 go to ZERO and the continuity to the mass in pin 1 ceases to be verified. The mass is made by the centralina, it seems to me that it is the ECU that is cutting the mass for some reason. I suspect a mass passage somewhere but I have not been able to identify the problem yet. I have tested with several ECU and the behavior is always the same.

Thank you.

 

Are you able to beg, borrow or steal a good quality code reader, you will need a quality code reader, Nanocom, Hawkeye or Lynx to access the MAF and engine ECU properly to check whether there is a MAF failure. MAF's often fail without warning as did mine 10 years ago and ever since it's been good. IMO never try cleaning a good MAF and only buy a genuine Bosch replacement as most others soon fail. If possible try to borrow a TD5 MAF off of someone else and test the system (but don't use a V8 MAF different ECU address and parameters) with a replacement before buying a new MAF. Also it may be an engine ECU problem (a common problem with the injector loom leaking oil into the ECU) or even in the MAF to ECU wiring. Good luck.