I have had an intermittent CEL on my X350. Came on a couple of days ago and disappeared this morning.

My previous S-type did the same thing. CEL came and went when it felt like it.

Anyone have an idea what it may be?

 

Read the codes. They're still stored.

You may be having misfires, as well or instead so check fuel trims as well.

 

Windsorlad111,

There are dozens of possibilities, so as JagV8 notes, your only hope is to have the diagnostic trouble codes scanned. Most auto parts stores will do this for free and they can usually read the Powertrain (P-prefix) codes that cause the CEL to illuminate. Often their scanners can also read the fuel trims.

Please write down every code they find exactly as it appears (e.g. P0300, P1316), and write down the Short Term Fuel Trims (STFT) and Long Term Fuel Trim (LTFT) at idle, 1500 rpm and 2500 rpm. Report all of that information here and the forum members will try to help.

At the link below you can download the DTC Summaries guide, which explains each code and gives possible causes:

X350 DTC Summaries

Cheers,

Don