I have the same problem, and I followed the advice of turning the ignition on x2 on 2002 Chrysler PT Cruiser

but no code pops up. Engine light does come on

Asked by for the 2002 Chrysler PT Cruiser
3 answers 2 comments
scan codes with a scanner and post so we can adv
ON-OFF-ON-OFF-ON........(3X) third time leave in 'run' position and watch LED display for 'fast' codes. NOT a substitute for a good scanner and proper diagnostics though. Must cycle key through sequence within 5 seconds or so , I believe.
Thought it was twice; I'll try that.
P 1684, and P 301
Looks like 301 is Cylinder 1, and 1684 has the battery disconnected in the last 50 start-ups.
Now to find which is cylinder one. I went 215 thousand miles on the first set of plugs; 15 on these
Reqires the use of a code reader or scanner to retrive fault codes.