Overheat light blinking on 1st morning start ? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

I was caught by surprise to see my light blinking when I started the car at around 40 Deg's,I changed the sensor probably 8 months ago..it has never blinked B4,..?? Thanks Frank

Four functions of the coolant warning light: 1. Engine coolant level too low — light flashes slowly (0.5 Hz) 2. Engine compartment temperature too high — light flashes slowly (0.5 Hz) (engine compartment blower might be faulty) 3. Engine coolant temperature too high — light is lit; pointer on the right 4. Temperature sensor at water outlet faulty — light flashes rapidly (1 Hz); pointer on the right Note The temperature warning in point three is indicated if the conditions "engine coolant temperature too high" and "engine coolant level too low" are present simultaneously (1Hz = 1 flash per second. 0.5Hz = 2 seconds per flash)

You are correct once again,I did ck fluid level but It was a visual ck look like it had enough...But 2 qt's of water later no flashing light !! Thanks so much ! saved me a bunch of guess work. it did have moisture around the cap so cap must be bad..its a 2 yr old factory tank and it's dry..Thanks Again ! JFP...Frank PS..going for the 3rd rad install soon,..or I would have used Anti-freeze

Look into getting the updated cap if yours is pre03. I recently had this issue on my 2000 and figured the cap wasn't holding pressure. Picked up the updated cap on amzn

JFP to the rescue again. I'm really glad you still post on here.

Thanks...M.W...I will do just that..Frank

Cold weather tends to mess with coolant level and/or coolant level sensor.

Would adding two quarts of water warrant concern to yall? I had the ole blinky temp light back when my water pump decided to start leaking, but mine was cut and (almost) dry the leak causing the low coolant levels. Could that much water have evaporated from the top of the coolant overflow in the trunk? If I remember right the seals can get old with age and allow moisture to sweat out from the top. Wouldn't hurt to take some of the trunk carpet out and just confirm your overflow tank isn't leaking. Seems like they're known to crack with age. I bought a spare from a Boxster part out just in case lol. Also, $40 for a clean low mileage one compared to the $300 for the part new!

I had VERY HARD TO SEE "spider cracks" in the coolant reserve tank. As the coolant got hot the increased tank pressure would cause the "spider cracks" to expand and coolant would collect under the trunk's raised flooring. The trunk carpet remained dry because the coolant would slosh around but under the trunk's floor, eventually it would drip out but only a few small drops at a time,and difficult to see. Every couple months I'd top off the coolant.....eventually I figured out what was happening.......I replaced my 20 year old tank.....problem solved.

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Sounds like what I am experiencing - thanks for sharing

If you think its similar to mine then: 1. Pull out all of the trunk liners (very easy) 2. Pull the raised floor panels (very easy) 3. Look for small areas pooling of coolant (it's possible that it might have evaporated or seeped out from a joint) 4. I wrapped the plastic coolant tank with a few layers of paper towels and drove the car for about an hour, until it was nice and hot. 5. Afterwards I pulled off the towels and discovered a few spots of wetness and coolant stains. At that point I knew I needed a new tank. From the reading of other postings, I ordered a replacement from Porsche thru my "indi" Porsche mechanic. (I was advised to avoid the lower cost aftermarket replacement tanks). All in, the tank, the labor, a couple of new hoses and clamps were about $900. I understand that some do it themselves but without a lift it's a much harder job, so I paid to have it done. My car is a 98' so the plastic tank was 22 years old....btw, I also replaced the old blue tank cap with the newer part number too.