Q: Crankshaft position sensor

If prior to the work, no diagnostic trouble code was set (i.e., check engine light was not on) identifying a fault with the crankshaft position sensor, then the likelihood is they caused the problem. In any event, once the "cause" of the new fault is identified you will definitely know one way or another for sure. For example, if the position sensor itself is faulty (that is determined using a scope; they can’t guess at it; it has to be diagnosed) and they did not come in contact with the sensor or remove anything adjacent to it, then they probably can’t reliably be blamed. However, the sensor works off of a wiring harness. If in doing other work on the engine, they loosened the connection to the sensor or damaged the wiring to the sensor, then it is their fault. It will just depend on exactly what is found as to the CAUSE of the code setting. Note that sometimes codes set, but the fault is NOT related to the part or parts identified in the code. Interpreting codes can be tricky and a code is NEVER (never!) a diagnosis. So, to answer your question, whether it is their fault or not will depend on EXACTLY what has, in fact, failed and whether they came in "contact" with what ultimately turns out to be the cause of that failure. You will find out, one way or another, because a Diagnostic Trouble Code referring, even in part, to the crankshaft position sensor will have to be tracked down and resolved. You definitely should request that they address and resolve the issue. If you have difficulty, you can certainly recontact us and request an engine diagnostic. Depending on what the mechanic finds, and can prove, you can then take up the issue with the shop that did the work and/or your credit card company if you paid by credit card. Please let us know how we can assist you further.