Someone brought me a 03 Mazda 3 to look at and while checking some unrelated things I noticed that the radiator fan was cycling on 15 seconds and off 15 seconds constantly, even though the ECT was reading a constant 88°C.
That just didn't seem right to me so I thought I'd ask if that's normal for this car?
The unrelated issues are that the car needs a new CAT ( P0420 verified ) and it's running a bit lean, LTFT of 14%, most likely a vacuum leak since it goes down to 5% at 3000 rpm.
LTFT, STFT, HOSB1S1, HOSB1S2, RPM, MAF, ECT
You can see that the temp stays flat all the time, even while the fan cycles on and off ( you can see where that happens by the MAF signal ).
Just seems a bit odd to me. A/C is not on, engine is warm after a 30 minute drive in the city. I'm wondering if maybe the ECT is reading accurately...
Unfortunately, I don't have access to the car for further testing.