In the exhaust manifold or downpipe
In the 1989 Grand Prix, the oxygen sensor is in the tail pipe. Look for a wire that is plugged into both the tail pipe and the undercarriage of the vehicle.
According to fordparts.com the 1989 Ford Mustang GT has ( 1 ) oxygen sensor
The oxygen sensor on a 1989 Chevy Celebrity is located in the rear exhaust manifold on top about the center.
The oxygen sensor is in the middle of the exhaust manifold near the firewall.
Left exhaust manifold.
The oxygen sensor for my 1989 190E 2.6 is located on top of the exhaust just underneath the passenger side of the car. The wiring from the 02 sensor runs up underneath the passenger side floorboard carpet.
install a new one!!
Check the manifold, just before the headpipe.
Toyota V6 1989 Oxygen senson is located on the driver side in front of the catalytic convertor. It has four wires and held on by 2 bolts.
Code 44 is an Oxygen sensor code meaning exhaust is to lean. Replace Oxygen sensor. Then clear codes. This should solve the problem.
All Oxygen Sensors are located in the exhaust eitherbefore or after the catalytic converter. Your O2 sensor may not be defective as a vacuum leak can cause the code.
According to my Chilton's Auto Repair Manual : For a 1989 Mercury Topaz ( front wheel drive ) ( 15.9 US. gallons )