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sprinkles08, ASE Certified Technician
Category: Australia Car
Satisfied Customers: 22807
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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My 2005 A Class W169 loses torque while the engine races.

Customer Question

My 2005 A Class W169 loses torque while the engine races. This is intermittent but is becoming frequent. I only travel a maximum of 3 miles per journey and it usually occurs at least once per journey. The problem is immediately solved by turning the engine off and restarting. There is nothing consistent about it. It can happen going down hill, uphill and on the level.
Submitted: 1 year ago.
Category: Australia Car
Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

If the engine revs up and no torque is applied to the wheels then the transmission is either slipping or disengaging completely. It may be as simple as low fluid level, it could be an electrical issue, a sticking valve in the valve body, or clutch failure.

The warning is coming on because the transmission control module is seeing an issue and setting a fault code. The first step in diagnosing the problem is to see what fault codes are setting. Do you know what codes are setting in the TCM?

Customer: replied 1 year ago.
Hello Sprinkles,
As I mentioned the fluid and gaskets etc have been replaced as the first option in trying to solve the problem. This car is usually driven by my partner so I have been repeating her description. However today I drove it to try and emulate the problem. Fairly early on within a few miles the problem occurred. The revs would not exceed 2000 and the gear was low as the speed was confined to about 15 mph. After restarting it was normal and although I drove suburban hilly streets for about an hour it did not happen again. As I mentioned the car is seldom driven more than 3 miles in a journey so could it only occur when the engine is relatively cold. I will ask the repairer about TCM codes. Other web sites I have visited describe this a common fault in the W169. I was hoping you would have experienced and have a more specific response as to the likely solution. Does this additional information suggest anything to you to justify my investment in JustAnswer.
Expert:  sprinkles08 replied 1 year ago.

I did note that the fluid was replaced.

There are dozens of things that can cause the transmission to slip, unfortunately without testing there isn't a way to know exactly what is wrong. If you can find out what fault codes are setting that may narrow down the possibilities, but in any case it will require testing in person to know exactly what is wrong.

Customer: replied 1 year ago.
Hello Sprinkles,
Unfortunately your answers have not given me any useful information. The car is now back with the service mechanics who changed the fluid and parts as previously described. They are conducting the fault finding tests etc. I had hoped that you would have actual experience of this problem and be able to cite the most likely solution that I could recommend to them. This is not the case so I can not give you a positive rating. I thank you for your attention but as you are unable to give a specific solution to my problem, I will seek the guaranteed refund under the 100% satisfaction guarantee.
Expert:  sprinkles08 replied 1 year ago.

I have extensive experience with this transmission but noone no matter how experienced can tell you exactly what is wrong with it remotely without seeing the vehicle just based on a problem description. The only way to know what is wrong, as with any repair on any system on any vehicle, is through in person testing.

Customer: replied 1 year ago.
I guess you have been saying that all along. However there are obviously questions that cannot be satisfactorily answered or guaranteed.
Thanks for your efforts.
Expert:  sprinkles08 replied 1 year ago.

Good luck with your repairs.