o2 sensor question

[Dhorn33]

When I bought my 98 GMC truck back in early December it had an SES light so I took it to Autozone and had them run a scan. It came back with code p0141 - o2 sensor bank 1 sensor 2. I did not replace the sensor but this morning I went back to the store intending to buy a new o2 sensor and had them plug it in again to verify the code. This time it came back with p0157 0 o2 sensor bank 2 sensor 2? The SES light is not always on - in fact it seems to come on for a few days then go off for a few days. The truck currently has 151k miles on it - and I have no idea if any of the o2 sensors have ever been replaced although when I looked under the truck it looked to me like the bank 2 sensor 2 was different from the rest - possibly indicating either it was a replacement or perhaps the others were replaced on that one was not. I don't really want to spend unecessary money on sensors that still function perfectly - so does anyone have any input on this?

[asilverblazer]

Sensor 2's are there to monitor catalytic convertor performance, not sure if the code means bad catalytic convertor or bad sensor. Either way I would start with replacing all the sensors, if the code persists then look into a new cat. I would do the sensors first because the fronts, might boost your mileage a bit. The rears seem to be going goofy so I would do all four. The hard part of that is the cost.

[abqchevyman]

It's likely that you have bad sensors. The heater seems to go out frequently and on the back side of the cat, the sensors really need the heat to read correctly (hence why they are heated). When the heater is bad in the sensor, they work fine, don't work, work fine, etc.

 

I wouldn't worry about the front sensors at this time.

[kdm101]

I recently came across some guy on ebay selling Delco O2 sensors quite cheap (new) since I'm planning to replace mine soon. In fact, it's a good enough deal that getting all 4 of them would make the most sense.

 

I've priced them through the local auto chains (online since the stores are rarely ever different) and was shocked at the cost for aftermarket units that were more expensive than I can get at GMPD!

 

Anyway, here's the link to this guy's ebay store. I'd recommend double-checking the delco part number from their web site using the part search feature and then search the ebay store for it.

 

http://stores.ebay.com/evalero1

 

FYI, for the NBS trucks with 4.8, 5.3, or 6.0L engines, front sensors are AFS138 Rear are AFS106 ($37 and $45 respectively).

[Dhorn33]

Thanks for the link to that vendor! I think I will order both the o2 sensors from there - it will be nearly $40 cheaper than anywhere else I have found for them.