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Matt
Matt, Mechanical Engineer
Category: Car
Satisfied Customers: 21995
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Going on motorway I have no power and light like a tap as come

Resolved Question:

Going on motorway I have no power and light like a tap as come on what could be the problem
Submitted: 3 years ago.
Category: Car
Expert:  Matt replied 3 years ago.
Hello

I'm assuming that this is a Turbo diesel version

On any car if you get a check engine light or other fault light this typically means one or more of the sensors has failed or has a faulty connection.

The fault can be something quite simple and nothing that’s going to stop the car to something quite major that will reduce engine power and possibly stop the engine

The ECU senses this and may put the car into 'limp home' mode which typically limits the revs and the amount of power available. Usually the car is safe to drive for a short distance as the mode is intended is intended to get you home without incurring any engine damage

The quickest route to repair is to have the car plugged into a diagnostic machine which will read off the fault code stored in the ECU (providing the light is still on at this point) and indicate which sensor has failed or whether the fault is more serious.

check the connections to the EGR valve, if either the vacuum pipe of electrical connection are damaged / corroded then the EGR can be on all time which certainly will hurt performance. Its also possible that its a fault with the EGR valve so its worth removing the valve and cleaning it out with brake cleaner, if it looks particularly clogged then replace it.

If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issues and its best to have the boost pressure measured actually measured with a boost gauge to check that the turbo is healthy and that the sensor is reading correctly

If its a variable vane turbo (they’ll be an actuator on the turbo body - but not a wastegate) then check its vacuum pipework as above and check the connections to the diaphragm / solenoid valve
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