Welcome to JA. We are working on a fast accurate answer. Your valuable time is very important to me. But a great answer has to well thought out. The exhaust leak is seprate from the traction control
most likely you have a bad speed sensor.
but to find out which one it is you have to have the hhr's abs traction control module scanned.
and this will tell you if its is a speed sensor and which wheel it is coming from or if it is a more serious issue.
what is the sensor on the back side of the transmission
there are out put speed sensors and other sensors back there.
but your traction would be read from wheels
the one on the tranny is for tach and speedo and such
there is oil residue on the left side of tranny. could this affect sensor
a little is normal.
as long as its not dripping
what causes this problem
if it gets on one of the electrical connections it can cause false readings
it can be dirt in the rotor or a loose connection to sensor or a bad sensor its self.
can the sensors be cleaned
it has to read all the spaces in the rotor and its magnetic. and every time a metal piece goes by it it reads it and compares it to other wheels readings and if there is a difference then it will stop it from spinning
yes they can if thats the issue
you can use electrical cleaner and compressed air and they will clean right up if would be good to get rust out of rotors also and that messy
I use compressed air and spray it and run away lol
once the cloud of rust dust goes down i go back
would this cause trans to shift hard when tc light is on
if oil is in connection on tranny and maybe if speed sensors on wheels had issues yes.