I have a very similar problem to the article below on my 96 Tahoe. Can the "relearn" process be done without going to a shop and paying someone??? RICK BULLOCK OF TORONTO WRITES I have a 1998 GMC 5.7L, 3500 dually. I had to replace the original engine due to rods knocking after 328,000 kilometres. I was on the road when this happened so I had no choice but to let a truck repair shop replace the engine with a GM crate engine. The truck runs well but the Check Engine light stays on and the code I get from my OBD II meter is 1345, crank position sensor. I have replaced this sensor twice and the camshaft position sensor once and the Check Engine light and code still exist. My question is, if they did not put the distributor back in the exact location as the original, would this cause this problem? If so, what or how can I eliminate this problem? ANSWER The trouble code 1345 indicates that the correlation between the crankshaft and camshaft sensors is out of sync; in layman's terms, that is a probable incorrect installation of the distributor assembly. Whenever a distributor is installed, the technician must use a scanner to interface with your vehicle and go through a procedure called "crankshaft position system variation relearn." This process instructs the computer to re-establish the correlation between the camshaft and crankshaft sensors. You should go to your preferred garage and ask them to do the following: Reset the distributor and then perform the relearn procedure mentioned above. After that, the truck should be back to normal. Any help would be appreciated.