Can the coolant sensor be tested?
 

I just replace the coolant equalization tank and sensor. Now the temp warning light is doing the slow flash. There's lots of coolant (used the Uview Airlift). So I'm thinking the new sensor is bad out of the box or got damaged during install. Any way to test its functionality in the car?

Congrats on changing out the tank, one of my least favorite things to do on a Boxster.

Sensor fully seated, plug clean and fully seated? Coolant level on full mark?

I'm having the same issue on my 996 that just had the tank replaced. I have a new cap coming tomorrow, so maybe that will solve the issue.....I don't know? It's driving me crazy. Waiting on a new SAI pump, so I'll also check the connection after I pull it out.

Do you still have the old sensor? If so, just install it and see if you have the same problem....

Yes, yes, yes and yes.

To say I'm a little annoyed is somewhat of an understatement.

I do still have the old one. I have to admit the old tank got knocked around a bit while coming out, so I'm a little leery of putting it back, with all the work and all.
If I could convince myself it was the sensor I'd just buy another one. But I don't want to go to all that if there's some other issue...

I didn't notice any flashing light when I first fired it up yesterday...

With my SAI coming tomorrow, I'll spend this weekend checking out the overflow tank. Pulling the SAI will give more clearance to check connections, etc... Maybe that combined with the new cap will solve the issue. If not, it's shop time and I'll send the bill to the dealer who was suppose to take care of the issue in the first place.

Actually installed the new (used) SAI today and wow, is it much quieter. While I had it out I gave the overflow tank a once over and all appeared to be ok.
I did install the new coolant cap with the newest version as it looked as though I had an original. The warning light did not go away, but I only drove it 4-5 miles. We'll see if it makes a difference.

It won't make any difference to your low level CEL. All the cap does is maintain pressure in the system - a failing cap seal lets air into or coolant out of the system.......

To complicate matters, you could have a problem with your engine compartment blower fan, which also displays a flashing light, as follows....

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).

Hope this helps.

Can the coolant sensor be tested?
 

My issue is that, prior to the tank being replaced, the light was never illuminated before. Perhaps I need a few more driving cycles to still purge the air. If that's the case, would I still see a low coolant light?

Is there any easy way to test the engine compartment fan?

Earlier posting removed. (I misread a member's post.)