I own a 2004 Sebring convertible with the 2.7L engine that burns regular gas. I have been having intermittent problems with my malfunction indicator light coming on. Using my inexpensive diagnostic tool, the error Code is P0158 which indicate a slow response for the rear bank O2 sensor near the catalytic converter.

The problem began a couple months ago after I had plugs replaced and the fuel system cleaned at a local mechanic. He proudly told me how when he ran the cleaner through the system that my engine blew a lot of smoke out of the exhaust. Then my problems began. Shortly after the work was done the MIL came on and I got the P0158 reading. The mechanic assures me his fuel cleaner has nothing today with the problem. I replaced both downstream O2 sensors, but every so often the MIL comes on. After driving for a few days, it goes off.

Usually, the MIL comes on if I have just been driving around town or idling when parked. The MIL will go off if I spend an hour or so driving steadily on the interstate.

Any suggestions on how I can correct this once and for all would be appreciated.

Thanks!
ArchtopBill
Asheville NC

 

P0158 = 2/2 O2 Sensor Shorted to voltage: Oxygen Sensor input voltage maintained above normal operating range.

Bank 2 is the front bank. Bank #1 is where cylinder #1 is located.

This could be a wiring fault in the wiring leading to the O2 sensor rather than a problem with the sensor itself.

 

How should I trouble shoot such a problem? Tracing the wiring harness looks tedious.

Is an ohm meter the way to go?

Thanks!

 

If you are satisfied that the problem is not with the sensor itself because you are sure you replaced the correct sensor with a known good one, and believe the problem is in the harness, I would not recommend attempting to repair the harness yourself. Oxygen sensors operate at very low voltages, less than 1.2 volts, and are very sensitive to bad connections. Unless you are skilled at this, it is unlikely that you can repair this circuit on your own to the point that it will work properly.
I would try replacing that front downstream sensor again to see if that might clear up the problem. Make sure the connectors are very clean. If that doesn't do it, get professional help from somebody who knows more than how to dump in a can of Seafoam.

 

I feel pretty good that I replaced both downstream sensors with "good" units. They were factory sealed Bosch sebsors and I took care not to touch the sensor itself, used the right socket to change and made good connections. I will try some contact cleaner on the connectors this weekend to see if that helps.

Thanks for the advice.