Hi, I have a Mercedes ML 320 Year 2000. Recently it starting to fail to start. I leave it 10mins then try again and then starts. Once it has stopped whilst driving it then waited 10 mins and started it and drove it home. Had RACQ put a console reader on it but said there was no error. This issue is getting more regular - at least once a week now. Also this week its starting to not change gear. Seems to be ok driving for 10mins then fails to change gear and stays in low gear. Would appreciate advice as is this an electrical sensor issue (crankshaft position sensor???) or stuffed electrics and gearbox.. Thanks, Carl.
Also forgot to mention that the SRS light comes on intermittently.
Hello and welcome to JustAnswer!
If the problem is intermittent and won't set a code then it could be quite hard to diagnose, but it sounds as if the problem is starting to happen more often which is good.
If no codes are setting it could be an engine controller issue. If the ECM isn't awake during these events then it wouldn't set a code. If it lost a power or ground feed, is failing internally or certain engine circuits short to power or ground it can cause the ECM to go down.
It's definitely possible that you could have a bad cam or crank sensor but either of those would normally set a code. Sometimes though it's possible for one sensor or the other to short internally and prevent the other from sending a signal also, which again would explain the lack of codes set.
If no codes will set then a couple things can be done. A data recorder can be installed on it which can be used to record ECM data at the time the problem happens, and then a tech can play the data back in the shop and see if they can tell anything.
Another option would be to leave it at a shop and allow them to drive it and see if they can get it to act up while a scan tool is on it, then they'll be able to see if a sensor signal is missing or if the ECM is actually going down.