P2101

P2101 is the range/performance variant of P2100 — the throttle-actuator-control motor IS responding to commands, but the position it ends up in doesn't match the position the ECM commanded within the allowed tolerance window (usually ±8% of commanded blade angle). On a drive-by-wire system there's no cable from the pedal to the throttle; the pedal is just two redundant potentiometers (APP-D and APP-E), the ECM does the math, and the throttle motor moves the blade. When the motor reaches a different angle than commanded — slow response, overshoot, or stuck partway — P2101 sets and the ECM drops to limp mode. Cheapest-first: pull the throttle body and clean it. Carbon buildup on the blade and bore creates mechanical drag that slows the motor's response below the ECM's expected slew rate, and this is the #1 cause of P2101 on engines past 60k miles. After cleaning, backprobe the TPS-A and TPS-B signal wires at the throttle body with the key on — TPS-A should sweep roughly 0.5V to 4.5V as you manually move the blade open, and TPS-B should sweep the opposite direction (4.5V to 0.5V) as a redundancy check. If they don't track in mirror image, the integrated TPS in the throttle body has failed and the whole unit gets replaced.

Vehicle-specific patterns: 2008-2013 BMW N52 / N54 / N55 is the textbook P2101 vehicle — the DME loses its stored throttle-adaptation values whenever the battery is disconnected without using the proper service mode, and the next start throws P2101 immediately because the blade-stop reference is wrong; the fix is a 30-second ignition-on relearn with the pedal untouched, or a scan-tool throttle-adaptation reset via INPA / ISTA. 2004-2009 Toyota 4Runner / FJ Cruiser 1GR-FE 4.0L throws P2101 from carbon-fouled ETCS-i throttle bodies that respond slowly; the $100 cleaning resolves it. 2006-2011 Hyundai Sonata / Santa Fe 3.3L V6 sees P2101 from a known TPS-internal-to-throttle-body failure under warranty extension in some markets. 2007-2014 GM 2.4L Ecotec (Malibu, Equinox, Terrain) commonly throws P2101 from a failed throttle-body actuator that needs full unit replacement (~$200 part). Critical: every one of these platforms requires a throttle relearn after cleaning or replacement — key-on / engine-off / 30-second wait / key-off / 10-second wait / restart — or the code resets within the first drive cycle.