Values of fuel system status:
1 Open loop due to insufficient engine temperature
2 Closed loop, using oxygen sensor feedback to determine fuel mix
4 Open loop due to engine load OR fuel cut due to deceleration
8 Open loop due to system failure
16 Closed loop, using at least one oxygen sensor but there is a fault in the feedback system

Source: https://en.m.wikipedia.org/wiki/OBD-II_PIDs#Mode_1_PID_03

 

Values of fuel system status:...
4 Open loop due to engine load OR fuel cut due to deceleration

A value of 4 occurring while driving is normal on these engines and typically happens on coast down with Fuel Cut Off to conserve fuel or under heavy load during acceleration most often above 3k RPM. The DME typically will go into and Open Loop condition above 3k RPM during very heavy or WOT. Closed Loop fuel control is too slow and not ideal for WOT. Not all engines have the coast down with Fuel Cut Off, but do change to Fuel System Status 4 during hard acceleration.

thanks .. i was wondering why it goes to fuel system status=4 during spirited driving. glad it is normal behavior .. i was afraid i was going to have to pull up my schedule for replacing the fuel pump and fuel filter.

 

Being able to Log and Monitor Fuel System Status is a very important data point. Many OBDII tools may provide this for Freeze Frame but not allow a user to Monitor and/or Log this PID. This is one area that OBDFusion shines and there is a reason that OBDFusion offers this feature, ask me how I know! I worked with the developer and requested this feature be added due to the importance of this for understanding exactly what the DME/ECU was doing. Seems that many OBDII App and tool vendors do not understand the significance of this very basic, but important data point and how critical it can be to have this available for the end user to monitor and/or Log.

A value of 4 occurring while driving is normal on these engines and typically happens on coast down with Fuel Cut Off to conserve fuel or under heavy load during acceleration most often above 3k RPM. The DME typically will go into and Open Loop condition above 3k RPM during very heavy or WOT. Closed Loop fuel control is too slow and not ideal for WOT. Not all engines have the coast down with Fuel Cut Off, but do change to Fuel System Status 4 during hard acceleration.

 

I know this is a very old post, I'm hoping some of the authors/contributors are still active.

I have a cold start rough running issue addressed in a different thread (OBD Fusion log (via datazap) of cold start and warm idle...) but I noticed in my cold start OBD Fusion log seen on Datazap here: datazap.me | apcrews | E46 330xi cold start misfiring, that my Fuel System Status for both cylinders goes to "8 Open loop due to system failure" about 107-130 seconds after cold start.

Does this mean I have bad oxygen sensors, or is it because of the cold start misfire, it can't figure out what to do?

 

I know this is a very old post, I'm hoping some of the authors/contributors are still active.

You can @ a member name in a post in your thread to call their attention to it.
For example: @boostd92

You’ll have the best support if keeping the info in that one thread, rather than posting in multiple threads.