I have a 2002 CLK 430 Cabriolet that I have owned for about 8 years. It just turned over 100,000 miles and has been very well maintained by me and the previous owner. I have an iCarSoft MB 3.0 reader that I have used to diagnose problems over the years. I use the 38 pin adapter for most systems, but can also use the OBDII port for the ECM if that's all I am interested in.

Earlier this week, I was in an unfamiliar location and I hit a huge bump that was not marked...no signs, no paint. Much worse than any speed bump. Everything appeared to be ok. Several hours later, I got on the highway to head home (about 160 miles away), when the Check Engine Light came on. The engine was running smoothly, there was no damage to the oil pan, and all fluids were full. I took it easy all the way home and made it without incident. The huge bump may not be related to the CEL.

For the past few weeks, when I started the car, it would idle very high - much higher than normal - around 2,000 RPM. I suspected that the throttle position sensor might be going bad. With the engine off, I repeatedly floored and let off the accelerator pedal. This seemed to correct the fast starting idle problem.

I connected the iCarSoft and found P0172 and P0174 codes (they may have been 171 and 173...I don't recall exactly and cannot pull codes now. Both codes were for the same issue on opposite banks. An online search suggested that the codes were due to a failing or dirty mass airflow sensor. I reset the codes and selected a relearn procedure on the iCarSoft. Starting the car everything was fine. The procedure required that I keep the car in 3rd gear and give it 50% power. I selected 3rd and accelerated. The car shifted 1-2-3 where it remained. When I stopped and began driving again, it was locked in 1st gear. Although the instructions on the iCarSoft were for a throttle relearn, it is clear that it was trying to do a transmission relearn. I stopped the car and went through the simple transmission relearn process. Everything went fine after that.

Yesterday, the CEL came on again.

I removed the MAF sensor and used Mass Airflow Sensor Cleaner to clean it. I then reassembled everything and connected the iCarSoft. It went through the diagnostics and I could hear various relays, fans, changes to the radio, etc. that confirmed that it was working. Then it indicated that there was a link failure and no connection could be made to the ECM.

I started the car and it ran smoothly and the CEL is no longer on.

Has anyone encountered a problem with an iCarSoft MB 3.0 suddenly being unable to connect to the ECM or anything for that matter? If so, what solution did you find?

I'm planning on disconnecting the battery and allowing things to reset themselves in the hope that I'll be able to connect again.

Any suggestions?

iCarSoft does not work on this car. I tried their nonsense extra adapter and yeah...their support is terrible too. Accusatory and terrible.