I have a 2005 ML270CDI with 170,000kms on the clock. Never had a problem until recently when it started to toggle in and out of Limp Mode. We use an ELM327 OBDII scanner with EasyOBD USB software. When I start the engine, all OBD values (e.g. RPM, coolant temp, intake temp, manifold pressure, etc) make sense, except for the MAF reading which is locked on 8.88 g/sec. After a few minutes of normal driving the MAF starts giving sensible values ranging from 6 to 150 g/sec. If I back off for a few seconds, the MAF will hover normally around the 6-10 g/sec marks for a little while and then lock on 8.88 again. Whenever the MAF is reading 8.88 the car is in limp mode, with 1/2 power, 3000 RPM rev limit and gearbox extremely reluctant to kick down. Whenever the MAF reading is constantly varying with values consistent with load at the time then the car has full power, full RPM range and normal gearbox behaviour. There are absolutely no stored fault codes recorded - which I find a bit strange for a 10 year old car assembled in Alabama by workers trained by Chrysler. In the olden days before OBDII we used to tap into the signal wire from a sensor to the ECU and measure its voltage or frequency directly. So if a MAF was outputting silly values then we could plainly see it. These days we depend on the ECU to tell us through OBDII what the ECU is interpreting from a sensor output. So it's possible for a sensor to be OK, but for the ECU, for its own fell purposes, to decide it's something else and give us that value instead. I have two questions: 1. Does the fact that the MAF intermittently locks on 8.88 indicate an intermittent fault in the MAF or is the ECU assigning 8.88 to it because of some other condition? 2. Is it normal for there to be no fault codes when a car is going in and out of limp mode?