Select cars to narrow search
dont search for 599cc fortwo modsdont search for 698cc fortwo modsdont search for 999cc fortwo modsdont search for roadster modsdont search for 453 smart modsdont search for forfour mods

Info guides and mods

Safe Mode

If the car senses that it is getting too much boost, it can panic and put the car into safe mode to protect the engine. So what could cause a car to suddenly create too much boost?

Modification Details

Over Boost

Over boost is when a turbo charged engine creates more boost than expected for the set parameters in the ECU.
When this happens, to save the engine from damage, the ECU runs a restricted set of parameters called safe mode.

In safe mode, the wastegate arm is either left wide open so boost pressure cannot be created
or the ECU runs restricted RPM, below the level at which the turbo would naturally create boost.

Excessive boost air could damage the pistons, the valves, head gasket, pipes to the engine and the turbo itself.
If it didn't enter safe mode, the car would have to do one of 2 things. Either run the engine lean to reduce
power which is no good for the engine, or increase the fueling to keep the ratio correct. Increasing the fueling
would increase the power the engine created which in turn would increase the boost even further.

So panicking like a little girl seems to be the best option for the engine.

More often than not, just turning the engine off and on again will reset the fault and allow you to drive properly.
The nature of the fault depends how quickly (if at all) the error returns. The fault will either be hardware, sensor
or software based although software is rarely the issue unless you have just had the car remapped.


The engine map in the ECU controls the air intake, boost pressure and the fueling.
Depending on how you drive, it will use a small set of many available parameters.
However, none of the parameters would normally create overboost.

So if you have just had a remap and the car keeps dropping into safe mode then firstly ensure
your air conditioning is off. Turn off all unnecessary electrical items (as long as it's safe of course,
don't go into full stealth mode at night) and see if it continues to go into safe mode.

Some older (shit) remaps had a problem with the car using too much power which the battery couldn't keep
up with. This created a power shortage (brown out) so the sensors didn't read correct figures. This fools the ECU
into thinking that there is a fault and the car goes into safe mode. Go back to the (shit) remapper and have
another remap loaded onto the ECU.... or get a refund and get it done properly by Tune 4 Performance.

Brown Out - Really?

Yeah, it's like a black out but not all the power is removed. Brown outs are bad news for electronics.
It's got nothing to do with the little bit of poo that pops out of you when your car suddenly goes into
safe mode whilst you are hammering it down the motorway with another vehicle right up your arse.


Well, not so much of the plural. Normaly it's just the 1 sensor that causes the problem.
Unsurprisingly enough, it's the sensor that measures the boost air pressure. The MAP sensor.

The MAP (Mass Absolute/Air Pressure) sensor is a piezo film sensor that deflects when pressurised.
The amount of deflection creates a varying voltage which the ECU can use to calulate the air pressure.

It's not unusual for the MAP sensor to become faulty and either give off an incorrect reading or no reading at all.
You can pick up pattern replacements off of eBay for £15. Fitting is 1 bolt and 1 connector. Easy.

There is also the possibilty that a faulty AIT (Air Inlet Temperature) sensor could misread the air temperature, causing the engine to run fuel lean or fuel rich. This can lead to detonation which is picked up by the knock sensor.
To combat engine dentonation (also called pinking), power is normally reduced by the ECU.

The same result can also occur if the knock sensor is faulty.


OK, now we are down to the engine parts. Normally a bit of a pain to get to, dirty, hot and hard to change.
Unfortunately, more often than not, it is one of the following that is causing the issue.


The rest of the information held in this guide is locked to members of Evilution only, you can login below or click this link to find out more.

Enter your login credentials here


Click if Info Helpful

Contact us about mod
Terms and Conditions
Site Disclaimer

© Copyright 2019, all rights reserved.