My ’94 C280 (172k miles) is sitting in my garage and won’t start. It lights up and sputters but it won’t start. So I had a mobile mechanic come by a couple months ago to see if he could get it running. I figured it would be worth the $50 bucks to get a pre-diagnosis and know what I'm dealing with before I started spending real money on a tow to the dealer, and the always pleasurable experience of them trying to sell me a bunch of work and parts that I don’t need. Any who…

He first thought the problem was the fuel pump. But after fooling round with it (manually making it come on), decided that was not the issue. After some time in the trunk and under the rear of the vehicle, he indeed got it to start several times. But the engine would shut itself off after running EXACTLY 30 seconds. (It did this three or four times like clockwork.) Every time he successfully started the car, just before turning the key, we would hear loud clicking/whirring/resetting type noises and then the vehicle would start right up. But only for 30 seconds. In order for it to start again, we would have to wait a while until we heard the clicking noises. And only after making those noises would it start again.

At one point he started the engine and it ran (roughly) for just over 4 minutes until we put it in gear (reverse) and it shut off. He restarted and it of course shut down again after 30 seconds.

Before leaving he pulled the code “P0600“ but had no idea what it meant. Nevertheless, he thinks the issue is something computer related/electrical. He believes the car thinks it’s being stolen and is shutting itself down on purpose.

As luck would have it, I have not been able to start the vehicle since he left. I’m not getting the clicking noises he was getting just before it would start.

Does anyone have any idea what is going on here? Any insight would be appreciated. Thanks for your time.