My wife's RX is really starting to give me a headache. The first problem I'm having with this car is detonation. The car starts pinging at part/ light throttle once the engine is fully warmed up. The is no CEL or codes pending. After scanning the car it seems that fueling is right where it should be and nothing else seems out of order. The pinging stops when you hit the gas harder. So far the only way to rid the car of this problem is to fill with 93 octane and that gets expensive with a daily driver. Shouldn't the knock sensors be handling this? Is there a way to test them?

The second problem I have is the heat won't turn off. Hot air always comes out at what seems to be low fan. I can move the area it comes from ( dash vent, floor etc) but I can't turn it off. With the fan set to off and no settings chosen I still get heat.

Does anyone have any ideas? The car currently has 78k miles on it

 

Where do you buy your gas? I don't have any issues with 87 octane gas now at 208k miles. I only buy from shell or Chevron, tier 1 gas stations. Is your RX Properly tuned up? Most People neglect to clean their Mass air flow sensor and fuel injectors. My RX runs considerably better after these 2 items were cleaned.

For your hot air issues, it sounds like your servo motor is stuck. There is a plastic worm gear inside that turns and is most likely, located behind the glove box. Search this forum or YouTube for servo motor worm gear.

 

Tune up on the car is good and mass air was cleaned. Car rattles on everything except 93 oct. And now I get water dripping from the driver side a pillar during rain storms. God I really hate this piece of ****

 

The air temperature coming out of the vents will always be directed over the heater core if you have the temperature set to anything but "cold". Turn the HVAC unit on, set it to cold, and switch it off. When driving its normal on all cars for some air to come through the vents.

The leak from the A pillar is from a clogged sunroof drain. Go from the top with the sunroof retracted and blow out all the debris with compressed air to clean it out.