yellow engine light at cold start

Just started up my 987.1 S after a long winter in the garage. Yellow engine light came on. Blinked twice then shut off. Drove it a couple of miles then returned to the barn. Engine light did not come back on. Any ideas?

Read codes?

It happened so quickly I couldn't get my reader in time. I have started the car a couple of times in winter to just barely operating temp. Never saw this till today. Engine oil indicator reads full.

Codes are usually saved for at least some time, so read them anyway and see what pops up. If it's anything important it WILL be saved.

Cool. I'll try that Thanks

Engine miss fire. But... it hasn't happened again. and it cleared by itself. I'll still have my guys take a look when i go in for an oil change.

Hey @jimsounddesign - If you're saying that the codes said an engine misfire, that makes sense that it did go away. When was the last time you changed your coils and plugs? If you've only got 46K on the Cayman, I'm guessing never? Might be an inexpensive and preventive step to take. Let us know how you get on with this. BTW - Although you've been on P9 for a few months, be sure to introduce yourself in the "New Members" section with some photos of your ride. It's kind of a strong tradition around here before asking tech questions.

I'll just add to FB's suggestion - starting and running the car just until it's barely at operating temperature is not a good thing to do, and probably is the cause of your misfires. When the car is cold the mixture is VERY rich (it's rich partly to keep it running, and also to fire off the catalytic converters). What shows as operating temperature on the dash gauge isn't. It's about 155F when it initially displays 175F (and it stays displaying 175F up to about 209F at least - that's as hot as I've ever gotten the engine...) The factory gauge is lying to you. I'd suggest that for winter storage, you hook up a battery tender , leave the frunk cracked open, either get cradles or increase the tire pressure to around 50PSI (avoid flatspots) and then walk away and forgettaboutit. You aren't doing it any favors starting and running it briefly. If you can't take it out and exercise it a bit - wait until you can. Oh - and add some fuel stabilizer to a full tank of fuel.

Taking a stab in the dark here but, you said the car had sat for awhile. The engine code was for a misfire, cleared itself, and hasn’t shown itself again. I’m thinking that during its down time, the fuel lines, from the tank, the fuel pump, the fuel rail and finally the injectors lost some prime or pressure, maybe even some evaporation right up to the fuel injectors and on the initial start the ECU or whatever reads and controls those parameter, sensed the loss of fuel line pressure, or failure to fire up immediately or in the proscribed time for a normal start sequence, and sent a message via the ECU resulting in the Check Engine light. I refer to those instances as a computer hiccup, short enough to send an error message, but not long enough to result in a true reading which would cause the Check Engine light to remain on. Best thing is, the light cleared itself and it hasn’t resurfaced. That’s the best outcome, would have been worse if it stayed on.

I feel your pain. I had an "event" recently on my 987.1 that did not result in any codes being logged -- although it clearly had a problem. I'd give it a good routine servicing (plugs, etc) then drive it carefully for a few short trips to see if it happens again.

My 2008 CS (43K miles) runs pretty rough after sitting for a few weeks when below 50oF (or so). If I start it briefly, turn it off and then restart, the idle drops and idles smoothly. I will get one or two misfire codes if I do not follow this sequence and just allow the rough idle to continue. Is this the same issue? Plugs have been changed, but not the packs. Chuck's thoughts make some sense especially when he issue is not seen when the car is being driven routinely. I guess checking the fuel trims before and after restart should provide some good data. Anything else to check with the Durametric? Can it give me real time fuel line pressure? Thoughts?

After taking to my shop, mu guy said coils & plugs were fine. However, the YELLOW engine light cam back on. Code PO421 (warm up catalyst efficiency threshold_bank01 Now I'm really confused. My shop said it was probably due to storing the car all winter. But, I did start the car in the garage for 10=15 seconds, then shut it off. No engine light noted. Anyone chime in here with some possible answers... Thanks

My Garage is heated and insulated. Temp averages 55 degrees all winter in Ohio.

Sounds like it could’ve just been a minor sensor hiccup after sitting all winter, maybe cold start-related or a brief misfire. If the light stayed off and it’s running fine, I wouldn’t stress. Still, it’s worth scanning for stored codes just in case something got logged.

I did scan the code. It reads PO421-Warmup catalyst below threshold-Bank1. My Porsche guy thinks is as you described above. He said if it keeps coming back on, he wants to dive deeper.

Yellow check engine light with a red ! in a 2006 Porsche Cayman S code PO421 This yellow engine light is driving me crazy. Possibly a o2 sensor post CAT on bank 1????

The code is P_zero-421. The basic codes go from P0001 to P9999. From AllDataDIY: There'ya go. It COULD be a catalytic converter - or not. Hope for not - the cats are very expensive, since they're built into the exhaust manifold..

I agree, hoping for NOT. It's headed to my local Porsche guy next week. He'll DME the fault and let me know exactly what's causing the "yellow" engine light. Thanks for your info. Very valid.

Do follow up on this thread when your local guy takes a look at it..

Thanks to all here for your help and advice. Th 987 went into the shop yesterday morning for a more detailed examination of the check engine light. My worst fears have been realized. Bank 1 CAT needs replaced.... $1750 including labor. My guys said if it was the bank 2 CAT that's bad. They have to order it from the factory. I don't get it. I've driven American cars to 60-70K miles and no bad cat. This must be a design fault by Porsche.

Given the symptoms - in this instance - I would have first shot the messenger to see if that cured the issue. The 02 sensors are telling the ECU that something is amiss. That could be something really is wrong or the 02 sensor is bad. I would have replaced the sensors - way cheaper than replacing the cat. Cats aren't known as a high failure point for Porsche cars.. lots of them out there working just fine at well over 100,000 miles just like American cars. Ricks Free Auto Advice is pretty good - but he missed shoot the messenger.. (old story about a general receiving bad news on the battlefield shooting the messengers who brought him the bad news.. it means there is the possibility that the equipment measuring the mixture pre and post cat has an issue. A really savvy mechanic will hookup to a good diagnostics machine and read fuel-trim numbers (reveals a malfunctioning injector), misfire counts and monitor the O2 outputs, recording them from a cold start to fully hot engine. If they're really good - they'll turn off the Check Engine Light before doing the monitoring run and watch for the light to turn on, and read the conditions when the light turns on.. Don't feel bad - this message happens and puzzles almost every mechanic. The dealership mechanics have the advantage of going to Porsche training schools where things like this error and common causes of it are taught - so in some cases - gasp - it may be less expensive to have a dealer look at it.