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Matt
Matt, Mechanical Engineer
Category: BMW
Satisfied Customers: 21975
Experience:  BEng hons Mech engineering, in auto industry 22 years
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i have bmw 520i 1999 eml light is on and speed limited to

Resolved Question:

i have bmw 520i 1999 eml light is on and speed limited to 60mph
Submitted: 2 years ago.
Category: BMW
Expert:  Matt replied 2 years ago.
Matt :

Hello

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 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.

You can do a very rough and ready check yourself by unplugging sensors one at a time and seeing if any of them change the driving condition which would indicate the most recently unplugged sensor is the faulty one. This method is not foolproof though and reading a fault code off is the better method.

Matt :

from your description I'd say it must be a major sensor fault or a lack of fuel pressure

Matt :

its also possible that the throttle body has failed so it no longer opens the throttle

Matt :

this one can be tested though, if yiou remove the intake pipe so you can see the throttle , then with the ignition on but engien off have your assistant slowly push down on the accelerator pedal

Matt :

the throttle butterfly shoudl open smoothly and slowly to fully open

Matt :

if it doesn't then get the codes read off as this will show if its the pedal or the throttle body itself

Customer:

how do you check lack of fuel pressure

Matt :

hello

Matt :

yo need a pressure gauge

Matt :

there should be a little test point on the injector rail

Customer:

ok thanks for ur help i,ll try that have a good new year

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