I have a Mazda 3 2004 sedan. It has 4 speeds. It has about 125,000 KM. I get all the normal oil changes done and brakes as these are normal. I noticed about a year back, from time to time the check engine light and the AT light would turn on. When the car is in park, and you move it to reverse it jerks. It shakes the whole car. It would turn on and then it would just disappear on its own. I didn’t think it was such a big deal. Then it came on again, and I went to a garage to get it checked out. He said that my transmission was done, and quoted me $900 for a rebuilt transmission. I just said ok and left. The lights disspaeared and took it to another mechanic. He told me the car is fine. It runs like a beauty and couldn’t find anything wrong with it. The lights continued to come on and off. For the past 2 days the check engine light and the AT light have been on. They haven’t disappeared. The car jerks from parking to reverse. It slightly jerks while shifting from time to time. I need to know whats wrong so I can get this fixed before it gets worse. I read some forums and they recommended doing a transmission fluid flush and someone else said, “The "Input Turbine Speed Sensor" is also called the "Pulse Generator" and is on the top of the tranny near the front of the vehicle and close to the engine. The part number is FN01-21-550. If you are getting a P0715 code, this is the one to change.” I need some advice please.
First, great job on keeping your car running for 125K miles!
It does seem like your transmission needs some maintenance. I've discussed this with our teams and they all recommend a transmission fluid exchange. Before you do this, however, replacing the sensor might fix this issue.
It is most likely a solenoid of some sort that is having issues. Now whether or not it is due to failing mechanical items within the transmission or a failing sensor itself, it would be hard to tell without testing those systems separately for voltage and resistance.
We would suggest replacing the sensor and running some diagnostics to confirm that this will fix it.
Check your owner's manual to see what interval is recommended for a transmission flush and based on your service records, it just may be time for this service!
Thanks for your question!
The Curry Team
〉 Answered on May 30th, 2012 by Judy Curry, Co-Founder and Vice President of Marketing at Currys Auto Service