A flashing the yellow transmission arrow accompanied by the check engine
light indicates the automatic transmission detected a problem.  This is
often accompanied by the car going into "limp" mode, which is the same
as "Winter" mode and the transmission stays in 3rd gear.  The "limp"
mode will normally reset the next time you start the car.  The lights
usually clear themselves in a couple weeks if it is not serious.  When I
had this happen on a '95 850, it was the "pnp" switch.  However, the
dealer replaced 1) the throttle position sensor, 2) the input speed
sensor and 3) the output speed sensor first which were perfectly OK.  I
have heard of other people having the same problem.  Bad "pnp" switches
are fairly common.  The code is usually 32x which indicates incorrect
gear ratio for gear x or in my case 322, which meant it occurred in 2nd
gear.  Since it only occurred on one gear, it should have directed the
mechanic to the "pnp" switch which detects which gear it is supposed to
be in.