Which Sensor has Failed?

[jcar]

2003 Hyundai Elantra

Hi. A while back the CEL came on and my mechanic replaced one of the 02 sensors. It was part # C5010111328.

Since then the CEL came back and I am now reading three error codes:

P0113
P0139
P0031

When I took it back he said it might be the other O2 sensor that needs to be replaced. Now, I am no expert but since the error code is for bank 2, I am guessing the downstream o2 sensor is what needs to be replaced, but I'm not sure. Moreover, I don't know what the other error codes would be for.

Since my mechanic is on vacation and I'm trying to get the car to pass emissions I'm trying to figure this out on my own and save some $ by not taking it into the shop.

Any help would be appreciated.

[only1db]

the p0113 is the air temp...which is the MAP sensor

the p0139 is slow response from the second 02 sensor

the p0031 is the heater circuit for the first sensor.


what needs to be done is a scan tool hooked so that you can look at the graphs of the 02 sensors....you can also check what the map sensor is reading as far as intake temps. Your not going to be passing inspection with those codes. It could be as easy as just replacing both o2 sensors...or you could have wires that have been corroded. Really dont know unless you back probe the wiring with the car on and watch what the signal does (for our cars the first and second o2 sensors are narrow band and will read 0-1v) other then that you'll be guessing.