For the last few months on rare occasions my car will go into a limp mode after the engine goes very lumpy. I could never get it diagnosed since on a restart the car would reset itself and go back to normal, and no error codes would show, but I finally caught it in the act and I got a P0339, an intermittent fault in the Crankshaft Position Sensor Circuit A. However the garage I took it to, to finally get that diagnosis said they wouldn't work on it due to the ecoboost's temperment with timing and cambelt issues, so I tried getting a quote from another garage and they also warned similar things about the cambelt stretching and causing issues, asking me when I last had the belt changed, which was mid 2024, and since then I've only put about 6k miles on the clock.

It's all got me a little be sceptical about getting a replacement sensor which seems like the logical fix. When I first had the cambelt done I did have to take it back since it was slightly out of alignment and I did get an engine warning light on the dash, but that was within the first week of getting it done and it's been fine ever since, so I can't see how it's suddenly being an issue now over a year later. Plus the fact that if it was a problem with the timing chain surely it'd be a p0016 or something along those lines, of a misalignment error code, I simply cannot see how an intermittent crankshaft sensor could possibly indicate a timing problem. But I just want to be doubly sure that I'm doing the right thing in getting a new crankshaft position sensor, and I'm not just wasting my time when in reality its a bigger problem.

Personally I'd go for the sensor if fitting myself and see what happens. Better to replace a cheapish sensor and it contributes towards a better vehicle in someway even if it doesn't 100% work. I'll always go for my own fix before handing money over to a garage. That's just me though someone might be able to give more sound advice