code 17

I ran the codes to the check engine light (cycle key 3 times. CEL was not illumintated during driving) just for the heck of it last night and got:

12
17
55

The 12 was from leaving the head lights on a few weeks ago, and the 55 is normal I know.

The 17 if I read right is "engine staying cold to long". Now the guage is always reading right up around 190-200 and warms up reasonably quick. There is a second CTS down on the engine block for the computer though right? Or is it just because it has only been 8-20 degrees outside for the past couple of days.

If I borrow an OBD1 reader will it tell me what the computer thinks the temp is?

91 XJ with 4.0L BTW.

Andy

The CTS for the PCM is in the thermostat housing, the one at the back of the head is for the gauges. The one in the t-stat run about $17 at Advance. I would replace it if you don't know when it was last replaced.

that fault is usualy set beacuse the thermostat is bad
pull the housing off and i bet the tstat is in pieces

justin

The heater works good and the guage reads normal so I don't think it is the thermostat.

The sensor locations are different then on a Renix then. This is my first time troubleshooting an HO system.

Borrowed an OTC System 2000 scanner tonight from a friend. His module was made in 89 so I told it that it was hooked to an 89 dodge truck. I was able to read all the other sensor voltages fine, rpm, selenoid states, ect... So that makes me think it was working with the XJs computer fine.

Anyway it said that the CTS was only reporting 120 degrees F. The dash guage was reading 200 and with it 13 deg outside the heater was able to cook my feet.

One positive I was able to use this scanner to turn of the stupid emmisions "maintenance required" light that comes on at 82K miles.

If the computer uses the CTS in the thermostat housing (is that right for sure?) I will clean the connector in the morning first and see if that makes a difference.

Andy

My '91 had the idiot gauge cluster and I had to change the sensor in the head, had a hell of a time finding one local, to get a reading on the gauge. So I know for sure the sensor in the head is for the gauge, that means the one on the t-stat housing has to be for the Computer.

Replaced the sensor tonight in 3 deg shop, I did it with the engine warm lol.

Scanner now shows the engine temp at correct levels. The Thermostat is opening fully around 203 degrees.

Starts better, idles smoother, and has better power. Hopefully my milleage goes back up as well.

Sensor was only $20 at carquest so if anybody has a rig that is flooding at startup this is what was causing my problem.

Andy

i just wanted to second this... i had a CEL code 17 as well, wouldnt take throttle and ran very rough, got worse with the colder it got.... replaced the coolant thermostat, and all is great... never would have thought this would have made that big of a difference, but it did