Came back from a trip where it sat for a few days. Start up my 2017 TD6 and it idles roughy where I can see the rpm dipping down. I’ve driven it fine for a few days and today it started doing it again at idle. What am I looking at as the culprit? Could a fuel pump be going or would that throw an error code? Could it just be bad fuel?

 

On a gas engine I would tell you MAF or vacuum. My TD6 just had to have its fuel pump replaced because it was literally leaking. I had it replaced under CPO (barely) but it was bad news, $7,300.