5.3 l Suburban Loss of Power

[Dale Lake]

My 2003 5.3 Suburban is experiencing power loss. It only happens when driving for a prolonged period of time (1 hour) in hot weather. The check engine light comes on. Codes indicate O2 sensor and low voltage error. The fuel filter was change, but did not remedy the problem.

[vncj96]

i would start checking all your O2 sensor wiring low voltage would indicate its not reading the sensor correctly or that there could be an exposed wire

[zubbiez]

Do you also experience loss of power going up hills? if so looks like the fuel pump could be goiong.

[Dale Lake]

Yes, the power loss is when pulling up hills. I replaced the fuel pump about 8 months ago. However, it was not the problem I had at that time (it was a head gasket). I could have a bad pump. I'll check the wiring. How many O2 sensors are there?

[vncj96]

not sure on the newer ones but my suburban has 4, you will have one in front and behind the cat, but you could have two cats thus making 4 sensors

[Delco99]

It might be an O2 sensor, but kind of sounds like it is overheating to me. Correct me if I'm wrong, but I think these engines have a "conservative driving" mode that kicks in when it starts to overheat.