S10 Oxygen senser P0155 code

[spanico]

I replaced the two precat 02 sensers and tried to clear the SES Code by disconnecting the neg terminal and removing the ECM fuse, But the SES remains on. Any help would be appreciated

[old_master]

A scan tool must be used to clear the DTC's and reset the ECM. Disconnecting the battery might turn the SES light off if there are no other problems, but the codes will remain in memory. If the light is still on, there is still a problem. P0155 indicates a problem with the circuit, passenger side O2 sensor closest to the engine. The DTC means there is a problem with the circuit, not necessarily the O2 sensor.

[spanico]

There were no other codes, only 155. I replaced both side o2 sensers, I can see the post cat senser, but where is the 4th one located.
Sorry for the ignorance but what is DTC?

[old_master]

What year is the vehicle and what is the engine code, (8th character in the VIN)? Some engines have 3 sensors, some have 4. DTC = Diagnostic Trouble Code.

[MT-2500]

Also check the fuse for the 02 sensors heater circuit.
Bank 2 sensor one is the one closest to engine on right side exhaust system.
Sometimes confused with bank 1 sensor 2.
Which is between front of cat and right side exhaust manifold also.
Follow the exhaust pipe from cat to the right/passanger side head.

[BlazerBrian99]

I had a 96' Blazer and all 4 o2 sensors needed change. The dio could never really figure what one was bad or good.

[spanico]

checked and replaced the O2 fuse and still have SES on, the 8th character in the VIN is W.
I tried the battery disconnect and leaving the ign switch on for 5 min, no luck there either.
The truck is 2002 with CAI and free flow muffler, the SES light came on the other morning after we had much rain and the morning was very damp.

[old_master]

There are only 3 O2 sensors on 2002. Disconnect the connector at the right side sensor. With the key in the RUN position, check for battery voltage on one of the wires in the vehicle harness. Check resistance to ground, (must be less than 5 ohms) on the two grounds. The fourth wire is the sensor signal wire back to the ECM.

[spanico]

we'll try that, thanks, I''l let you know

[spanico]

Finally got rid of the SES light, I broke down and bought a actron reader and erased the DTC, the home remedies didn't work. Thanks for the help