Took my blazer to my moms mec. told me the p0300 code from my engine was prob the crankshaft sensor. i already changed plugs and wires. sooo I bought a new one went home to change right away. SURE ENOUGH, i pull out the old sensor it was damaged crankshaft must have been hitting it. PUT NEW ONE IN AND NOTHING....... 1 shim 2 shim still nothing. wont even start know it was at least running. put the old one back in and started right up... and it looks damaged... took sensor back to oriellys got another new sensor came home NOTHING AGAIN... oh but wait old one still works. why wont the new ones... PLEASE HELP...

 

Almost unheard of for a crankshaft position sensor to cause a P0300, and nearly impossible if there was not a DTC for the sensor.


If/when the crankshaft position sensor and/or timing cover are moved, removed, replaced, or disturbed in any way, the crankshaft position sensor relearn MUST be performed with a scanner capable of initiating it, (auto part store scan tools can't do it).


The sensor creates a magnetic field when voltage is applied to it. When the spikes on the tone ring, (on the crankshaft) pass through the field, the sensor generates a pulse. Among other things, the PCM uses the pulse for injector and ignition timing. The sensor air gap has to be correct, or the sensor will not generate the pulse. If the sensor is in too far, it will be damaged by the spikes when the crankshaft rotates. If it's out too far, the spikes will not pass through the magnetic field. Best to use an AC Delco sensor, (they fit pretty good). Bottom line, when you get it running, you will need the relearn done, then we can go after the P0300

 

Thank you for the info. I guess im stuck in my drive way with it then. i already removed the sensor. new one wont fire the blazer up. yea he said dtc p0300 I believe. I know there was a dtc he talked Guess Ill get the old one back in and try and make it somewhere to find a relearn code. Thanks for all your help. from what i've seen and read on here you sir are awsome. do I need to do anything eles after this or should it work after this??
Thank you

 

sorry little slow here. just makin sure. hope the old sensor gets me to where i need to go, to a scanner to relearn the code?? wonce I make it there, were ever that is lol. Put the new sensor in and before i try to start or crank the motor over rescan the system for that part or code to relearn. Blazer wont even start with new sensor I hope it dont need to run to re learn.
Thank you so much for all the help. New to the blazer world.

 

If/when the sensor is disturbed, replaced, etc, the engine should still start and run. However, injector and ignition timing will not be correct and as a result, the engine will not run as well as it should.


If you have an accurate micrometer, you can measure the distance on the original sensor from the shoulder to the tip. This will help determine which shim to use, if any, on the new sensor. I can't remember ever seeing any shims being used on OEM sensors, that's why I recommended the AC Delco.


The crankshaft position sensor relearn is quick and easy, when you have a scan tool that can initiate it . It literally takes longer to load the vehicle information into the scanner, than it does to do the relearn. Once it is initiated, the relearn takes about 5 seconds to complete. You'll need to check around in your area to find a shop that has a capable scan tool, and technician, to perform it. After it's done, nothing else needs to be done, as long as you don't disturb the sensor


P0300: It is usually, but not always, is caused by a fault in secondary ignition, (spark plugs, plug wires, distributor cap, rotor, and ignition coil). AC Delco parts need to be used, with the exception of the wires and the coil. Those two don't necessarily need to be AC Delco, but they do need to be good quality. If you need part numbers, just ask.

 

Thank you so much for all the great info. Think Ill replace with ac delco and find a shop to relearn the code.

 

There is no "code" to relearn, just a data relearn. The sensor creates a magnetic field when voltage is applied to it. The field is directed at the tone ring, and it is "focused" in a very small area. The focus area of each sensor is unique. The relearn "tells" the PCM exactly where it is focused in relation to the tone ring spikes as they pass through the field. The relearn data is burned to a file in the PCM, and it remains there until the next relearn is performed. Each relearn overwrites the previous data. Disconnecting the battery does not affect the data file, and the only way to change the data, is by performing a relearn. The crankshaft position sensor is accurate to roughly 20K RPM, almost 4 times the red line of the engine, should be sufficient for the grocery getter


You'll need to tell the shop that you need a "crankshaft position sensor relearn". Also known as a "CKP sensor" relearn. I've also heard it referred to as a "CASE" relearn, (not sure why though).

 

Cap'n, whats a good brand of wires and coil other than AC Delco?

 

Name brand quality parts like BWD & Echlin coils are fine. You really don't need "high performance" stuff. Autolite Professional series wires have better specs, and are cheaper, than AC Delco. Good stuff. Stay away from house brand el cheapo stuff at the parts stores. Basically don't buy your groceries at the parts store, and don't buy your parts at the grocery store

 

I had my crank sensor changed today and it didn't require a relearn. I have a 2001. Was I just lucky?