2000 s10 blazer 2 door 4x4 185000 miles. Runs good has all kind of power for about 25 minutes or20 miles then starts losing power. What happens is it loses RPM if your easy on the gas you can limp it along as soon as you step on the gas at all it almost stalls out. Let it sit for awhile and it will run good again. Flashes code 131 and sometimes 151 which are oxy sensors. Would bad o2 sensors make it run like this or i it something else that is making the o2 codes come up I recheareced this and really didn't come up with much. Thanks all in advance

 

P0131 - HO2S Circuit Low Voltage Bank 1 Sensor 1
P0151 - HO2S Circuit Low Voltage Bank 2 Sensor 1

Problems with your O2 sensors can definitely cause it to run poorly. I would be more concerned about your catalytic converter at this point. It sounds like your converter may be partially plugged and causing the performance issues.

Most exhaust shops can do an exhaust pressure test before and after the catalytic converter to assess its health.

 

This is what's going on ur O2 sensors are sending either a too ric or lean code to each side causing it to misfire so to answer your question yes it is possible to have a O2 sensor make your truck run bad. Now an easy trouble shooting solution would be remove the 2 O2 sensors that are giving you the problem they Are the 2 closest the the exhAust manifold And swap them with the sensor before he cat and after the cat if the code moves to bank 1 sensor 2 or bank 1 sensor 3 then the O2 sensors are bad, also get some wd40 and spray inside the connectors and dry them out after I hope this help

mullahey Chevrolet fullerton CA

 

A 2000 does not have the pre-cat sensor. GM did away with the pre-cat emissions monitoring sensor in 1998.

Be careful if you try to "dry out" the sensors using some WD40. You would be much better off using an electrical contacts cleaner that dissolves the water and evaporates it away if water intrusion is a concern.

 

It's not called a precat O2 sensor but it does have another O2 sensor before the cat and wd40 does work and it's cheaper also for O2 the electrical conductor cleaner isn't the best to use due to the fact it puts a "film" on the connectors for "better connection" but it causes just a slight more resistance than what's needed and it will trigger a code for it.

 

I am sorry, but you are incorrect. There are only three O2 sensors on the 98+ 4.3L engine. Two upstream (B1S1, B2S1) and one downstream (B1S2 or B1S3 depending on year). It was sometime around '01 when the downstream (post cat) sensor name changed from B1S3 to B1S2. This change in name corresponded with the addition of the pre-cats in the exhaust piping.

Here is an illustration straight out of the FSM that applies to all 98+ trucks:



I won't debate with you in this thread about the potential problems you are opening up when using WD40 on the electrical connection to the O2 sensor. Suffice to say, an O2 sensor breathes through the wires. You can figure it out from there.

 

Thanks for the replies. Guess I will have to have the cat checked then the o2 sensors

 

kyle my 2000 has an 02 sensor on both sides of the exhaust. but i didnt see any after the cat and since i had to cut the exhaust pipe from the y pipe and after the cat where is the 3rd one at ???

 

As shown in the illustration above. The downstream (post-cat) sensor should be located right behind the catalytic converter. I do not have my old Bravada anymore or else I would go snap a picture at this location for you. Maybe someone else can help in that regard.

 

i looked again from the exh manifolds to the tail pipe. no post cat sensor.
is there a chance gm screwed up and forgot the 3rd 02 sensor ????
we all know gm screws up. remember the chevy corvair.