I've got a 1991 964 C4 and the CCU was replaced with a 993 version. I'm getting a recurring fault code 16, which is an unlisted code. The CCU ID is H08ITR, 99365904701.

Has anyone seen this code before? Someone years ago mentioned that it could actually represent fault code 21, which is the oil cooler temperature sensor, but that seems odd.

 

[H08]
;Climate control trouble codes
11=Inside temperature sensor
12=Left mixing chamber temperature sensor
13=Right mixing chamber temperature sensor
14=Evaporator temperature sensor
15=Rear fan temperature sensor
16=Outside temperature sensor
21=Oil cooler temperature sensor
22=Defrost flap motor
23=Footwell flap motor
24=Fresh air flap motor
31=Left mixing flap motor
32=Right mixing flap motor
33=Left heater blower motor
34=Right heater blower motor
41=Condenser blower motor
42=Oil cooler blower motor
43=Rear blower motor speed 1
44=Rear blower motor speed 2
45=Inside sensor blower motor
46=Rear blower motor speed 1
47=Rear blower motor speed 2

The outside temp sensor is placed in the left vent opening in the front fender. If you have the OBC tachometer there's two identical sensors there.
Cheers,
Tore

 

Tore, you are the CCU expert!! Thanks for the info. The only outside temperature sensor I could find on the 964 is in the secondary motor blower duct that's in the left side of the engine bay. PN 96465912000. #12 in the picture below. Could this be the correct sensor even though you mention a front sensor?

I found a post from you in 2013 where you said that early 993's and 964's don't have an outside temperature sensor for the CCU and that in order to have the later 993 CCU better control of the interior temperature this sensor could be installed. I am using CCU ID is H08ITR, 99365904701, which is a 993 CCU in my 964. If this is the sensor that is throwing the fault, do you have a part number as I couldn't find one in the 993 PET.

I appreciate the help with this.

Cheers,

John

 

Well.....I bit more research and I finally found it as item #10 in the below picture for the late 993's. Which leaves one important question. The 964 probably doesn't have the wiring to plug and play the outside temperature sensor. I could probably fab something up, but is it worth the time and effort? From what I've been able to find, the OAT protects the A/C from turning on when it's too cold and the interior heater from turning on when it's too hot.

Cheers,

John

 

I am sorry, I wrote the above in a hurry this morning.
Yes, the 993 CCU will throw this code if the sensor is missing, but the unit will operate normally. I would not bother to wire up an outside sensor. What is more important, is that all needed wiring changes is done to get this unit working properly in the 964. There's 4-6 wiring changes needed, depending on the part number of the original unit and the new unit.

By the way, if you use the Scantool software you will see the fault code text description if you use the 993 cfg file.
Cheers,
Tore

 

I figured it would a hassle to set up an OAS. Thanks for verifying. Good point about using the 993 configuration file.

JP