How many 02 sensors are on a 89 chevy c1500... codes 43 and 44 are coming up they both speak of o2 sensors and i know nothing bout vehicles

Here's a link to check out. How to Diagnose P0135 Heater Performance Bank 1 Sensor 1 GM 3 5L

There is only one sensor in the 1989 Chevy C1500 John you need to check the ground on the ECM

Hello there are two 02 sensors on this vehicle, 02 sensor 1 {pre 02} is located in the rear exhaust manifold. the second 02 sensor {post} is located in exhaust pipe just behind the cat. converter

O2 sensor cross talk bank to bank irregular, change 02 sensor(s).

Sounds like Idle air control sensor bad, All of your codes interact, I would start with 02 sensor.

I would locate a Tech II and run a diagnosis, eliminate guess work.

i have an 2007 chevy uplander flexfuel i keep getting p1174 also i have replaced the the o2 sensors and the light keeps coming on
i belive it has something to do with the fuel injection system

Make sure the Coolant temp sensor for the computer is actually working right.  Its the one next to the thermostat housing, it has nothing to do with the gauge.  When they go they usually don't throw any codes because they kind of work enough (same with the O2) to throw way to much fuel at the motor when it's hot, causing flooding out, stalling, etc. and of course it's no good for the O2 or the catalytic convertor. 

there are 4.

It is the o2 sensor itself replace 02 sensor. Keep in mind you have four of them. the computer will tell you which one has the fault example. bank 1 sensor 2 If I can help anymore please repost with engine size I will be happy to help DRIVE SAFE TIM

there are two 02 sensors actually on the engine. bank one is cylinders 1 3 5 bank 2 is 2 4 6. it controls the fuel to air ratio, if the O2 sensor is not working, the engine goes into limp mode, which means it is just putting as much fuel as possible into the cylinder, which will effect your gas mileage.

The O2 sensor may be fine, the pigtails off the 02 sensor go bad, the connection. I had in my car, i change the 02 sensor twice, then I found someone said the pigtails may be bad, so I cut the cars wiring harness pigtail, and the one coming off the 02 sensor, and directly wired it with the original truck 02 sensor, and it worked. all 02 sensors look similar, they screw in the side of the engine, and just have 4 wires coming off of it.

Try your origional one, and just bypassing the original wire connector, what I did was cut it off, skinned the wires, put some heat shrink rap on it, combined the wires together soldered them together, and heated the wire shrink rap, so that way it is water proof. car works perfect now.

what codes ? probably timing chain worn out