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MB Paul
MB Paul, Mercedes Technician
Category: Mercedes
Satisfied Customers: 4317
Experience:  Mercedes Benz Qualified Diagnostic Technician
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my B180 cdi the auto sometimes locks into lower gear with warning

This answer was rated:

my B180 cdi the auto sometimes locks into lower gear with warning on display, switch off engine, restart then it can be ok for sometime

MB Paul :

Hi, my name is Paul & I will try to assist you

MB Paul :

The transmission locking into a gear & not shifting is a sign that it has gone into limp mode - this happens when the transmission detects certain faults & stops shifting to prevent any further damage. The fact that is resets after switching the ignition off & on again indicates that this is an intermittent faut - the transmission will remain in limp mode until switching off & if the fault is not present when restarting then it will shift fine until it detects a fault once more

MB Paul :

There are many possibilities at this stage & the first step in finding the cause of limp mode is to have the vehicle checked on a diagnostic tool such as Mercedes STAR - the system will have stored fault codes which will help pinpoint the cause of your fault

MB Paul :

A common problem on this model is the speed sensors on the valve body but there are a wide range of other causes which will give the same symptoms

MB Paul :

Let me know if you need anything else

MB Paul :

Best regards, Paul

Customer:

Paul. I am not able to find your answer

Hi,

sometimes the system causes problems in live chat mode so I have switched this off

see my answer below:

MB Paul :

Hi, my name is Paul & I will try to assist you

MB Paul :

The transmission locking into a gear & not shifting is a sign that it has gone into limp mode - this happens when the transmission detects certain faults & stops shifting to prevent any further damage. The fact that is resets after switching the ignition off & on again indicates that this is an intermittent faut - the transmission will remain in limp mode until switching off & if the fault is not present when restarting then it will shift fine until it detects a fault once more

MB Paul :

There are many possibilities at this stage & the first step in finding the cause of limp mode is to have the vehicle checked on a diagnostic tool such as Mercedes STAR - the system will have stored fault codes which will help pinpoint the cause of your fault

MB Paul :

A common problem on this model is the speed sensors on the valve body but there are a wide range of other causes which will give the same symptoms

MB Paul :

Let me know if you need anything else

MB Paul :

Best regards, Paul

MB Paul and other Mercedes Specialists are ready to help you