po156 & po157

2004 4x4 2500 6.0,28,000 miles. just pulled codes p0156 &po157 points to o2 sensor defective in bank 2 any ideas or just replace sensor. runs just fine with no problems otherwise except for the engine light stays on all the time now

You should get a scan tool that can read live data and look at the O2 sensors.

Both of those codes refer to the 02 sensor in bank 2 (pass side exhaust) sensor 2 (aft of the CAT). Sensors do go bad even with only 28k. So, if you want to replace that sensor ($$) without doing some more testing go for it.

P0156=Sensor malfunction
P0157=Sensor detects a lean condition.

You might want to try disconnecting the NEG batt cable for about 10 mins to clear the codes and the SES light. If the light comes back on and you get the same codes you'll know. It may have been just a transient "glitch"

I'm not really sure if that will help with your '04 as I'm more dialed in to the older ('99's) models.

Might still be under warrenty if only 28,000 mi.

Same thing happened to me at about 30,000. '01 5.3l I cleared the codes and they never came back. Live data on my scan tool shows the sensors to be within normal limits.

disconected battery for 20 min but light still on. did not reset