[seanswn]

Hi Gurus,

I am having this weird issue where the auto start stop will only trigger once per drive.

So let's say I start my car drive to a traffic light, the auto stop works, then drive to the next traffic light it will show the icon as per image.

It will work again if of shut down and turn on my car again for 1 time.

The car is a N20 528i, automatic.

Any ideas? ISTA+ show no error.

[Hoa]

When auto stop start is crossed out, your vehicle’s current state is not ideal so it disable it to prevent a potential drain that could not start the vehicle again. For example: battery may not be at ideal condition, too hot or cold outside where AC or heat is running and draining the battery too much, etc.

[seanswn]

True, but since it always able to trigger the auto stop 1 time after each start. It hard to identify which condition caused it not to trigger the 2nd time.

[Qsilver7]

There are prerequisites for ASS:

Prerequisites of an automatic engine shutdown

The automatic engine start-stop function will only stop or start the engine if certain prerequisites are met.

Engine shutdown

The engine is switched off when:

• The vehicle is stationary (speed < 0 kmh).
• The engine speed is virtually at idle speed.
• The vehicle has been driven at > 10 km/h since the engine was last shut down.
• The vehicle has been driven at 10 km/h since the last change at terminal 15.
• The brake is pressed.
• Steering wheel movement is not moved. Steering wheel must be aligned straight.

And there are also ASS shut off inhibitors…you’ll have to determine if any of these inhibitors are occurring:

Switch-off inhibitors

The engine continues running although the vehicle is at standstill and held with the brake pedal.

The following preconditions act as switch-off inhibitors and prevent the engine from shutting down:

• Engine adaptation (e.g. cylinder adjustment)
• Regeneration of the diesel particulate filter
• Carbon canister needs purging
• Insufficient knock resistance of fuel
• Engine fault
• Engine coolant temperature
• below a defined value (depending on engine version approx. 20 ‐ 60 °C)
• above a defined value (depending on engine version approx. 100 ‐ 130 °C)
• Automatic transmission not ready
• Gearbox adaptation active
• Drive position “S”, “M”, “N”, “R”
• Driving surface incline too great
• Assist system active (Active Cruise Control, Parking Assist, Hill Descent Control)
• Stop-and-go driving
• Last MSA stop was too long
• Air conditioning requirements:
• Automatic air conditioning: MAX AC button pressed
• Automatic air conditioning: Defrost button pressed (request to defrost the windscreen)
• Air conditioning system: high blower speed and low blower temperature, compressor button pressed
• Air conditioning system: high blower speed and air distribution directed to windscreen, compressor actuated
• Ambient temperature ≤ 3 °C
• Engine speed > 1200 rpm

• Battery condition:
  • State of charge too low
  • Measured battery state of charge not plausible
  • Battery temperature too high (approx. 50 °C)
  • Starting voltage drop from previous ASSF start too low
• Vehicle rolling

[seanswn]

Thanks, based know what I observed, mostly is the battery. Thanks for all the advice!

[Qsilver7]