SB200 Code 3 is back.

[Dlinniy]

Hello. A year ago, my SB200 popped codes 3 and 11. With the help of people on this forum I was able to clear it when i got back in town and replaced the return air temperature sensor. Now, a year after, I am in the same situation, loaded with temperature controlled freight, and codes 3 and 11 come up, the screen shows it's 36F inside but i used my good old thermometer and it shows 44F. Now I've cleared the codes and am waiting to see if the temp changes to what it is supposed to be at. When I get back home I will have to take another look at that sensor. Now my question is about the service life of those sensors. Like I said, I replaced the old one a year ago and during this last year only put about 2500 hours on the unit. Could this be something bigger than the sensor, is it normal for the sensor to go out every year, or is my unit just acting up with those codes for no reason? Also, is there a test chart or something with resistance values for the sensor at given temperatures so I can test it with an Ohmmeter and be able to tell that it is indeed the sensor or do I need to look further and could I please get it emailed to ruslsobr@gmail.com. Thank You!

[IRMechanik]

Best way to test a sensor is to drop it in ice water. There should be enough harness there to do this and leave it hooked up. Controller should read right on 32 degrees.
I'm assuming you set the sensor grade into the controller when you changed the sensor since it's been working ok until now. Was it an oem TK sensor? the oem one's aren't great but the aftermarket ones are complete rubbish.
Could be another bad sensor or it could be pins at the micro are a little loose.

[Dlinniy]

Thanks for the reply.

No, I did not enter the sensor grade into the controller when I installed it, I did not know about the procedure, nor do I know how to perform it. I did it myself because my local TK dealer had a 3 day wait for service and they also wanted to charge me 4 hours worth of labor to change the sensors out. Do I need to hook up the controller to a computer to enter sensor data?
Yes, it was an OEM sensor, bought it at the TK dealer, came in TK packaging, but it seemed a bit larger than the one I removed. I just cleared the alarm code 3 once i reinstalled the sensor, and it all worked fine. Hauled a few loads with a temperature recorder, customers never had any complaints. BTW since I cleared the code this morning, reefer has been running fine and the temperature reading on the controller matches what my good old thermometer is showing. I am thinking it might indeed be loose pins or something else, but I will definitely do the ice water test when I get unloaded. Thank you.

[gravy258]

you need to enter the grade via guarded access on the micro.
turn on, hold TK and clear buttons at same time, scroll to DDUR45, hold TK and clear, next screen wil take you to sensor grades. it will be the one with RA under the grade, scroll up/down arrows to get a match to your new sensor.

[Dlinniy]

Thank You very much, gentlemen!