What P2021 usually means
P2021 is the Bank 2 low-signal version of the intake runner position feedback family. The PCM is receiving a lower-than-expected signal from the Bank 2 runner sensor or switch, which can be caused by a short to ground, missing reference voltage, poor ground, sensor bias, or a runner that is physically near the low end of its travel. The goal is to decide whether Bank 2 really is parked low or whether the feedback circuit is making it look that way.