P0513

P0513 means the PCM (or the immobilizer module talking to the PCM) received a transponder key signal that does not match any of the keys currently programmed into the vehicle's immobilizer memory, so the engine either will not start, will start and immediately stall after two seconds, or will start once and refuse to crank again. This is not a sensor failure; it is an authentication failure. Cheapest-first ladder: try every key you own one at a time to rule out a single failed key (the transponder chip in the head can crack from being dropped), then verify the key is being read at all by watching for the security telltale to extinguish within one second of key-on. If the light stays on or flashes a slow blink, the immobilizer antenna ring around the lock cylinder is not detecting the chip, which on most vehicles is fixed by reseating or replacing the antenna ring. Caveat: this code is overwhelmingly the result of a recent PCM, ECM, or BCM swap where the replacement module was never married to the existing keys.

Vehicle-specific patterns: 2000-2010 Chrysler, Dodge, and Jeep vehicles with SKIM (Sentry Key Immobilizer Module) are the highest-volume case after used-PCM swaps, requiring a locksmith with DRB-III or Witech to relink keys to the new module. 2002-2008 Ford F-150, Explorer, and Mustang with PATS need a Forscan or IDS session with two known-good keys to program a third. 1998-2005 Volkswagen and Audi with the immobilizer-3 system require dealer-level access or specialty tools to add keys after a cluster or ECM swap. 2005-2012 GM full-size trucks with PassLock can throw this after a steering column or BCM swap and need a 30-minute relearn. Estimated repair: $60 to $400.