Hi, this is Bo, an auto expert on RepairPal's Car Genius team!
Wow, you've really dived deep into this P2101 gremlin on your QX80 – props for the thorough research and troubleshooting! That code coming back after a month is like a sneaky houseguest who only shows up when you've almost forgotten about them, making it extra tricky. You're right, P2101 points squarely at the Throttle Actuator Control (TAC) motor circuit, so your focus on the throttle body and its associated bits is spot on.
Given that the code is intermittent and you've covered the basics like cleaning and visual checks, a couple of things come to mind. Even if the throttle body looks brand new, the electronic motor or the integrated position sensors inside it can develop intermittent faults. It's like a perfectly good-looking lightbulb that only flickers occasionally – the problem is internal. The fact it's not going into limp mode might mean the issue isn't constant or severe enough for the ECU to hit the full panic button, but it's definitely noticing something amiss.
Before you bite the $600 bullet for a new throttle body, if you have access to a good scan tool, monitoring live data for commanded throttle position versus actual throttle position could be enlightening. Look for any discrepancies or lag, especially if you could try to replicate conditions that might have been present when it previously set the code (hard to do with a month interval, I know!). Also, check the freeze frame data stored when the P2101 code last set; it can give clues about what the engine was doing at that exact moment. Sometimes an intermittent wiring issue, despite looking good, can cause this – a slight change in resistance or a momentary open/short. Unfortunately, with these integrated electronic throttle bodies, if the fault is internal to the unit, replacement is often the only fix. It's a tough call trying to avoid guessing on an expensive part.
If you need any further advice or want help finding a trusted RepairPal shop in your area, please feel free to call us at 877-913-1554
