Despite cleaning engine air filter daily, sometimes twice, I got trouble code of engine intake air flow problem. Can't remember actual code. Couldn't believe it was engine air filter. Cleaned engine air intake, since it had some leaves restricting air flow. Didn't help. Back to shop, cleaned engine air filter, and trouble code cleared.
Never had dirty engine air filter problems with T870. Only a problem with air flow sensor's wires making bad connection.
Not sure how others are cleaning their engine air filters. I start by banging round sides of filter on any outside flat surface. Followed by (suggested by Bobcat person), using a Leaf blower inside air filter to blow remaining dust out (reverse of normal air flow).
Bobcat needs to get on top of filter problem. The engine air filter cylinder chamber needs something similar to Cyclonic action of bag-less vacuums, to separate dust and dirt, before reaching primary air filter. Intake air, needs to be pulled from some place other than near engine cooling fan's exhaust grill.