Diagnosis of Code P0340

[YotaFun]

Well I stopped at Wal-Mart today to Check out something.
Get back to the truck, starter starts acting up, which is nothing knew I know its time to replace it.
But finally I get her to turn and she turns and fires really quick Like I think I had to hold the key a second and she was running, which was odd to me, so I look down at the dash, and wouldn't you know it, my all time favorite light was on.
So I turn the truck off, get my code reader out of the back and pull the code which happen to be a P0340, Crankshaft Position Sensor Malfunction.
So now I am sitting in my truck (which was conveniently parked close to the entrance) throwing out of my mouth every curse word Imaginable.
So I start the truck back up again and drive slowly towards home, at a stop light I shifted it into neutral and shut if off, when I went to turn it back on,it turned on and the CEL went by by.
The past few months the truck as been giving me false CELs it seems, For instance, I pulled a code once for a faulty front o2 sensor, I did an oil change and some seafoam and its been almost 5k miles since I have gotten that code (still have a front o2 sensor on standby IF the issue returns).
The engine sounds normal to me, idles right, accelerates right, no weird noises or anything.
I check wires and all nothing looks to be shorted or anything.
Is there any other way to diagnose that the sensor is going or is it just a wait and see process?
How badly will my engine be damaged if at all if the sensor where to go?

All of these issues are on a 97 Runner SR5 3.4l 4WD Auto.

I personally think my electrical system is shot to hell for some reason and I just want to gut the thing some times...

Anyway,
Thank You in advance for all answers and tech tips,
Avy

[4runnerchevy]

I know nothing of the crankshaft sensor, but my guess it is a normally open magnetic switch that closes when steel passes in close proximity to it. If this were the case, and is easily removed, it could be tested with a meter. As far as testing o2 sensors there is a good write-up on TTORA, heres the link.

http://www.ttora.com/wiki/index.php/Oxygen_Sensor_Test

[20005spd]

if your starter is giving you issues and is giving you a hard or extended crank. then your crankshaft position sensor code could have been caused by that. that code will not hurt the engine, it rarely will make it run weird either. first thing you need to do is fix that starter. most of the time people get away with replacing the brushes in that starter, its really cheap.

as far as the o2 sensor code i wouldnt worry about it till it comes back. what was the code on the o2? there is no such code as faulty o2 sensor. oil change and seafoam has nothing to do with that.

[YotaFun]

I was just going to bump this thread the second you posted lol!

The started will be changed when the truck is in for a new timing belt and water pump.

As for the o2 sensor code, I will see if I stored it in my code reader, all I remember is saying was bank 1 sensor 1 slow or no response, and when I had to replace my rear o2 sensor I got a code that said it was malfunctioning.

When I get out of class I will check out the reader.

[YotaFun]

Well I am SOL on the code for the o2 Sensor.
If I saw a list of the codes I could tell you.

[20005spd]

eh, dont worry bout it till it comes back :thumbup:

[YotaFun]

Yeah, that will be the plan, Thanks again for the help and the ease of my mind :-)

[4runnerchevy]

Most readers will say upstream or downstream O2 sensor!