NOTE: This only works if you have the EGR delete already done from here: https://forums.mercedesclub.org.uk/index.php?threads/disabling-egr.68928/. (It could be made to work if you still have EGR, but you may need to put a 470 Ohm resistor between MAF pin 5 and EGR PWM signal at the ECU end.) Are you sick of going into limp home mode all of the time? Are you having trouble finding a genuine MAF sensor amongst all the fakes? Are you burning through expensive genuine MAF sensors at an alarming rate? Then you've come to the right place! I decided to try this mod after a spate of early failures on genuine Pierburg MAFs on some ML270s I maintain. New genuine MAFs here cost $250 a pop, and the best I was getting out of them was 6 months. But this simple circuit emulates a MAF just fine on my ML270 (and presumably other CDI2 based vehicles as well). All you do is connect a 5k6 resistor and a standard diode in series, between the 5V Reference pin and MAF signal input pin, at the MAF sensor connector (pins 4 and 5 respectively). Then you just leave the MAF sensor unplugged. The way it works is that it provides a valid MAF signal to the ECU. The MAF signal pin is a high impedance input to the ECU, so a tiny current flows from the +5V pin, through the resistor, then it gets dropped by about 0.7V by the diode, then the ECU sees about 4.3V on the input. This voltage corresponds to a ECU MAF reading of about 540mg/Hub using star diagnostics. This is at the top end of the range expected by the ECU depending on air temp and barometric pressure. This allows the ECU to run without any restrictions due to the MAF reading. When EGR is activated, the EGR delete circuit comes into play... Now the 20mA or so current flows out of the +5V ref MAF pin, through the resistor, and through the diode, where it gets read by the ECU again, but this time there is a 470 Ohm resistor there from the EGR delete circuit which pulls down the voltage via the ratio between our new 5k6 Ohm resistor and the EGR delete 470 Ohm resistor. This results in a MAF reading of around 200mg/Hub. This reading tells the ECU that the EGR is working as expected and prevents EGR faults from being logged. This is the entire circuit, simply plug it into your MAF loom connector and buy yourself a beer or two with the $250 you just saved. I made mine so that the legs of the components were shaped and soldered like the pins on the MAF sensor, so they fit snugly into the MAF loom connector. You can also play with different resistors and diodes if you find it still gives you codes. I also tried an LED with an 3k3 resistor and it worked fine as well. But I switched out for the above because it was too bulky with the LED. The key things are: You need a diode to drop the voltage below 5V when in non-EGR mode, and you need a resistor to divide down the voltage when the EGR is active and its 470 ohm resistor is pulling pin 5 down. PS. anyone concerned about the job of the MAF on these... don't. Its only there so that the ECU can detect EGR malfunction, this is a requirement of EURO2. The ECU also may or may not have a maximum fuel limit map based on MAF, but that would only normally come into play if the MAF reading was very low, for example a heavily blocked air filter, or blocked CATs. But in that case the MAP/IAT sensor combo will cause the ECU to limit fuel appropriately anyway. One thing is for sure the ECU loves putting the car into limp mode when the MAF sensor fails. This mod prevents that. If you are still worried, know that my 316CDI Sprinter has the same engine and ECU as my ML270, but it comes without EGR from the factory. And hence it doesn't have a MAF sensor from factory either.