I am starting to get some erratic pressure readings on the dash computer readouts the pressure was reading 16 lbs,but when we used a tire gauge the pressure was 39 lbs. the car is a '09. does anybody know how long the battery in the sensor is good for, and can the battery be replaced or does the unit need to be replaces? and about how much are the units? thanks

 

Use the search tool. More than likely the problem is that the sensor positions have never been reset after new tires or rotations, thus you are adding air to the wrong tire. Check all of the tires. Read your Owner Manual for directions on resetting the positions (may not work if your HHR was a rental in it's former life).

 

When we bought the car, the sensors were not reading pressure for the correct tire. the sensors were reset and now read for the correct tire, they read 32 to 34 lbs on the dash and 36 by pressure gauge

 

So your problem has been solved....correct?

In some cars you will notice a difference between the dash readout and an physical check with a tire gage. !-3 pounds is not unusual.