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Matt
Matt, Mechanical Engineer
Category: Mercedes
Satisfied Customers: 20611
Experience:  BEng hons Mech engineering, in auto industry 22 years
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my 10 year old mercedes e320 d will go into safety mode only

Customer Question

my 10 year old mercedes e320 d will go into safety mode only if im in slow mooving trafic i turn off engine start again to reset it its fine if im not in trafic had it linked up to computer and its somthing to do with turbo but they dident know which part
Submitted: 2 years ago.
Category: Mercedes
Expert:  Matt replied 2 years ago.
Hi

do you have any of the fault codes that they pulled off with the diagnostic?
Customer: replied 2 years ago.

turbo and catalytic clogged up but it runs fine dosent heat up there isent any smoke it goes in to safety mode if iv been in traffic then when clear and i exselorate it dose it

Expert:  Matt replied 2 years ago.
Hello

if the issue only occurs at idle and goes away under load then its quite possible that the issue is an airleak after the airflow meter, any air dragged in here isn't 'seen' by the you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.
Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.
Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine


Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.
if the engine condition is the same then chances are the meter or the connection to it is faulty

Air leaks are very temperature dependent as gaps can open or close up as things expand with heat, so the weather and engine temperature can effect them.

This leads them to be quite intermittent in the case of mild leaks

its also worth cleaning the airflow meter by removing it from the car and spraying the exposed sensor wires inside the tube with a brake or switch cleaner - ensure that the cleaner is one of the old fashioned, non Eco type that does not leave a residue

On no account touch the sensor wires with anything physical as they are extremely fragile

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    Matt

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