| I have a 1993 325i with a burnt out O2 sensor. Do I really need to replace it? How much will it cost? How difficult would it be for me to do it myself? |
I have the same car, '93 325i E36, M50 engine and I just replaced the O2 Sensor this past weekend.
If the "Check Engine" warning light is illuminated and you've checked the codes (turn ignition to 2nd step, depress accellerator 5 times in less than 5 seconds, count "Check Engine" pulses and it flashes code 1221) you may need to replace the O2 Sensor. It could also be a loose gas cap or in my case I had a cracked fuel sending unit that was leaking gas when the tank was full causing the "Check Engine" light to illuminate AND flashed Code 1221 (O2 Sensor). When I replaced the fuel sending unit located on top of the gas tank along with the seal, the "Check Engine" light went out.
Since I was tuning the car up anyway, I replaced the O2 Sensor as part of routine maintenance.
I bought mine online from Peilcan Parts for $101.75 (part number BW-11-78-1-735-49, a Bosch Unit).
How difficult? Replacing it is just a matter of unscrewing the electrical connector on one end and unsrewing the O2 Sensor from the exhaust system (sensor is located near the transmission on top of the exhaust system).
But be forewarned, the sensor is usually a bitch to get loose and you'll need a special "shorty
" 22mm combination wrench that you can pick up at Sears for $13.99. Part Number 44130 in the Sears Tool Department.
A standard 22mm combination wrench is too long to work in the confined space where the sensor is located on my car.
You can also purchase a special 22mm "slotted" deep socket that has a portion of the side cut out so that you can slip the socket off of the sensor wire after you've used the socket to tighten the sensor. I couldn't find the socket locally so I went with the wrench from Sears.
You'll also need a tube of anti-sieze compound to use carefully on the sensor threads. This will make removal the next time easier.
You'll also need to either jack the front of the car up and place on jackstands or use drive up ramps or a lift to get under the car to access the exhaust system.
I did the entire sensor replacement in about 10-15 minutes which included getting the tools together and placing the car on drive up stands.
You can do it easily. Breaking the old sensor threads loose is the toughest part.