Engine light is on

50208 Views 46 Replies 14 Participants Last post by Timothy Muir, May 6, 2014

eslite.louis

Discussion Starter · Oct 30, 2013

I bought a CLA250 on last Friday ( 10/25/13 ). Three days later, my engine light was on on the way to my office, the mileage was around 296 miles.

This Monday (10/28/13), I drove back to the dealer, and they said someone has the same problem, and has already noticed the Mercedes. It is a program issue, it won't effect the car and safety; now the engineers are trying to fix up the problem with re-programing. Once they are done, they will let me know so I can bring the car to the dealership to install it.

They told me this before I sent it to the maintenance, I don't know if they were trying to avoid me to get the official record or what? Right now I'm still driving the car with the engine light on.

Any suggestion? What should I do right now?

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ClarkL

· #41 · Apr 2, 2014

coder said:
Hello,

I have done it both ways, and find the trip computer fairly accurate. I am using premium (93 oct. Mobile) and it does not look they topped off the tank. The weather is a bit warmer recently than it was before the ECU update.

In any case, I see the numbers improving recently. I think the issue was : the ECU update resets to factory defaults. It looks like, it takes some time for the computer to re-optimize its settings based on observed data. I have now 150 miles racked up since the update, and I am almost back to where I was before. (Getting close to 38mpg on hwy now).

I would be really interested in what kind of experience other folks had, who had the ECU update done.

Odd behavior then. On my old turbo diesel VW, what you describe would be called "limp mode" where the engine management system defaults to air and fuel flow that will definitely work but leaves the car feeling like a limp noodle on the road and get very poor economy.

I guess this might also explain why the first fuel tank in my car was only able to get me about 2/3 of the distance the tank gets now. It must have been learning then too.

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coder

· #42 · Apr 3, 2014

I think limp mode is a bit different. The ECU detects a problem and intentionally limits engine performance to minimize a chance of damage.

The car will not on its own recover from limp mode w/o some repair.

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coder

· #43 · Apr 6, 2014

200 miles later, my fuel economy is back to where it was before the ECU firmware update.

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ismail

· #44 · Apr 7, 2014

Nice

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coder

· #45 · Apr 18, 2014

ECU reflash update, mpg better now

Update: Changed oil at 6K. Magically, my fuel economy improved.

I am getting 40+ mpg on highway as long as I keep it under 80mph,
and do not drive too aggressively.

If I keep in under 55mph on cruze control, as high as 44 mpg on my regular commute from Raynham to Nashua ( About 75 miles)

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ismail

· #46 · Apr 18, 2014

All my cars have shown improved fuel econ after the first oil change

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Timothy Muir

· #47 · May 6, 2014

my CLA has 3600 mile and has developed a problem. i went to pass a car and the car started bucking, the check engine light came on. i had it toed to dealer they said they re maped the computer but it started doing the same thing again. they have had my car 2 week and at first said it was # 3 injector but replacing it didn't fix it. they can't figure out how to fix it.
has anyone had these kind of problems?

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