my service engine light came on and i took it to autozone to check out what the problem was and they said it was one of my front o2 sensors or somethin like that they said it could be the wiring or maybe i jus need new 02 sensors. i want to knwo where exactly the 02 sensors are located and what i should do before i decide to buy new ones......99 trans am .......i have an exhaust cutout right after my catalytic converter would that have anything to do with it ???? ......

 

What ecxactly was the code #?

 

They should've been able to tell you exactly which sensor was causing the problem from the code. There is 4 o2 sensors. One in front and one behind each cat.

 

code was p0135

 

The P0135 is HO2S Heater Performance Bank 1 Sensor 1. Which is driver side pre-catalyst sensor. It's located above the catalytic converter on the drivers side.

First thing I would check would be the fuse in the underhood fuseblock. Make sure it's not blown. If the fuse is fine, get under yur car when the engine is not hot, and disconnect the drivers front O2 sensor.

With the ignition on, grab a test light and make sure you have B+ to the sensor (PCM side) by probing the pink wire using a known good ground (not the 02 sensor ground).

Also check to make sure you have a good ground by probing the ground (black wire) with the light powered up from the IGN B+ (pink) wire. If everything checks OK, keep reading.

Measure the resistance of the heater (IGN and GRD) circuit AT THE SENSOR pigtail. If your meter reads OL then you need a new O2 sensor. If it reads within 3.5 to 14.0 ohms, then the heater circuit is good in the sensor. If it is good, then check all of your wiring and make sure there aren't any opens or short to grounds between the sensor and the PCM.

If all the wiring is good and the heater circuit checks good, make sure all of your connections are tight and free of any corrosion or debris. Make sure that the terminals in the connectors arent pushed back at all. This should about cover it, good luck.