My love-to-hate-it relationship with the Solstice continues.

I was having some issues with apparently-random warnings (ABS light, weird DTC, gas cap warning when the gas cap was not loose). The issues temporarily (for a few days) disappeared. Since an autocross last Sunday, I hadn't seen any weird behavior. (However, even though the ABS light was not on at the autocross, the brakes locked up a few times.)

Today, my CEL came back on. I hooked up the scanner:

0x7E8: P0171 - System Too Lean (Bank 1) (Pending, Current, History)

0x7E8: P0420 - Catalyst System Efficiency Below Threshold (Bank 1) (Pending, Current)

0x7E8: P0455 - Evaporative Emission System Leak Detected (gross leak/no flow) (Pending, Current, History)

0x7E8: P0507 - Idle Air Control System RPM Higher Than Expected (Current)

0x7E8: P0563 - System Voltage High (Pending, Current)

0x7E8: P0621 - Generator Lamp Terminal Circuit

I suspect a bad ECU. Even the alternator warning (P0563, P0621) appear to be harmless, since the battery is definitely getting charged. The car starts right up.

Oh, and I noticed yesterday that the tach doesn't really work for about the first 10 seconds after start. The needle just sort of bobs up and down about 5ish degrees.

Definitely some sort of electrical gremlin. :/ All the grounds I've checked have been fine, but there are a lot of them so it's possible I've missed one.


I pulled the alternator yesterday, and saw this. Not sure how I missed this when I pulled it off of the old engine. It's worth noting that the previous motor threw a rod from the #1 cylinder. I think the rod grazed the alternator.

enter image description here

Looks like there's a short in the coil.

  • Nice question! Good data. Apr 6, 2016 at 16:21
  • Could there be a ground that wasn't connected or that was damaged with all the work you've been doing? Or a pinched harness?
    – JPhi1618
    Apr 6, 2016 at 17:21
  • @JPhi1618 very possible, but I haven't found it. I looked at all the ones that are easily visible and nothing looked out of place or suspicious
    – 3Dave
    Apr 6, 2016 at 17:47
  • Have you checked the charging voltage? If it's high your battery will overcharge, and you may not notice until the electrolyte boils away. High voltage can also trigger false codes.
    – TMN
    Apr 7, 2016 at 11:40
  • Do you live in an area with a lot of small rodents? Like squirrels, mice, etc.
    – race fever
    Apr 7, 2016 at 12:27

1 Answer 1


Oh wow, there's definitely something funky going on with the electrical system.

With regards to the P0563 and P0621, have you tried getting a live reading of the voltage from your scan tool or a multimeter when the car is running?

My advice - get a decent automotive electrician on the case. Your run of the mill mechanic isn't the right person for the job

  • I was going to do that, then I remembered I am a trained electrical engineer. Which means I know just enough to blow myself up. Definitely over-charging. Thanks!
    – 3Dave
    Apr 10, 2016 at 14:24
  • How do you mean overcharging? The alternator is pumping out too much voltage or current?
    – Nick
    Apr 11, 2016 at 12:21
  • Voltage. I didn't measure current. Added a pic of alternator damage to my post.
    – 3Dave
    Apr 11, 2016 at 13:28
  • "Grazed the alternator" is a bit of an understatement :-)
    – Nick
    Apr 12, 2016 at 16:22
  • 1
    It was "grazed" in the same way two freight trains colliding head on "graze" each other.. :)
    – cdunn
    Aug 26, 2016 at 20:52

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