2007 Mazda3 Leak Detection Pump Run Schedule

Feb 26, 2009
Upstate NY
This is an odd and a difficult question, but I still want to ask the board. I have this car from new (one owner) and know all maintenance history (I do most of maintenance). I also studied the service manual and understood how the leak detection works.

In early years, the LDP would run some hours after the engine was off, all was good. Starting roughly around 2018, I have noticed that the LDP would run immediately after the engine off, every 2 full warm-ups, clock work. I don't think this is a good timing for running LDP. It would interfere with refueling for whatever reason I have to refuel before the low-gas light comes on. It would also not a good condition for such a test as fuel in the tank is not quite settled. Service manual listed the conditions for the leak test (but did not indicate how long after engine off). Other conditions include ambient pressure, intake air temp, fuel level (15% to 85%), and battery voltage >10.9v.

No DTC whatsoever. I wonder if the PCM logic has a change on its own (say after certain mileage it would switch to a new schedule), but no reason for this change anyway. If you have a Mazda3 at this vintage, would you listen to the right rear wheel area right after the engine is off to confirm that I am not the only one? If you are an experience Mazda tech, please chime in as well. The LDP runs about 2 mins. And the PCM has no knowledge whatsoever if the fuel door is open or the fuel cap is open to abort the test.

My gut feeling is that something somehow changed the PCM logic. In the service history of the car, battery was drained a few times, disconnected more times (mainly for changing certain parts, i.e. spark plugs, fuse panel removal on passenger side for cabin airfilter change.)

Thanks for your time.