RebelScum

Hey all

Just bought my first Merc this week: 2005 CLK 320, 170k Kms, black-on-black, fully dealer serviced its entire life. Super happy, but it gave me a scare yesterday.

I made a short stop. When I got back in the car (15 minutes), I turned the key and the engine cranked but wouldn't turn over. I tried again; same issue. 3rd time, same issue. I opened the door about to get out, changed my mind, closed the door, tried again, and it fired up no problem, but the CEL came on.

I drove off and made another stop 10 mins later. When I came back out after another 10 mins, the car started fine and the CEL was off, and it's been fine ever since.

A quick search here tells me it could be the CPS (best case) or the fuel pump (Worst case). I'm hoping it was some kind of one-off glitch. I'm 13000 Kms away from Service A, but now I'm concerned I should make an appointment and take it in.

If this was any other car (read: less electronics), I'd look at the MAF, the O2 sensor(s), the fuel mixture ratio, even the air filter. But I'm kind of all thumbs when it comes to Mercs. Any help here is appreciated.

What do you think?

Rudeney

CPS would be my guess. If it does it again, try pouring cold water on the CPS (back of the engine, just on the left side of the MAF sensor and throttle. Also, since you had an MIL, the code is probably still stored, even though it cleared itself. Id pull codes to see.

RebelScum

Cold water? What does that do?

Rudeney

Heat is usually the culprit of a failing CPS.

RebelScum

Interesting. Good tip, thanks!

The problem hasn't repeated in 3 days of solid driving (gawddam it's hard to keep that car parked) but I do hold my breath a little every time I turn the key.

I have a couple of freelance invoices outstanding...maybe when those come in I'll treat her to a day at the spa.

xcoleman

It is definitley your CPS. As a matter of fact, my car is at the dealer at this very moment having the CPS replaced, I have an 03' CLK 500. About a month ago, I had to get the fuel pump replaced and then the car not starting issue happened 3 weeks later. You definitley need to have it replaced soonest.

~Xaviera~

RebelScum

I'll get that looked at before the snow hits. Last thing I need is to be left stranded in a Canadian Blizzard. Those are the worst kind.

I also need to make an appointment to have my passenger seat controls looked at. They were working fine until I pitched the seat forward to let someone in the car; now they're dead.

I was fiddling around with them last night and I got an occasional response from them, so the motor clearly works; feels like a loose connection. From what I read here, I gather those connections are SUPER delicate and fail often. I'm guessing I only need to take the door card off and secure the wires...what say you, Internet?

Rudeney

If it is the CPS, cold weather is usually not a problem.

As for the power seat, keep in mind that there is not a direct-wired connection between the controls on the door panel and the adjustment motors. The switches connect to a computer inside the door (door control module) that in turn sends coded signals down the CAN bus to the computer in the seat (seat control module) which then actuates the motors. If it were a bad switch, it would likely only be one of them that failed. When they all fail, it's most likely a problem with the seat controller. Since it started when the seat was folded forward, it might be that some of the wiring on the seat controller was disturbed. Check under there to make sure everything is properly connected. Also, makes sure the seat has properly latched back in place - tilt it forward again, and then slam it down firmly back in place to make sure it latches and triggers the microswitch to register that it's back in place.