Codes 1684 & 0123 - What did I do?

[EDGEFIND]

Alright, I fully admit that I'm pretty ignorant to the technical aspects of newer vehicles but being hard up for cash and having some mechanical ability I decided to take a stab at my wife's PT. It's her daily driver and, unfortunately, I only get to see it when there is a problem. The other day I noticed a coolant stain on the garage floor where she usually parks and asked her about it. She said that the coolant level has been dropping but she keeps it filled. At least she did that. I took a quick look at it when she got home and was able to see it leaking all around the thermostat housing and cover so I went ahead and picked up a new thermostat and o-ring to replace what was in there. I followed the Haynes guide step by step in removing the upper manifold and everything and then replaced it all putting everything back in reverse order. Now the engine light is on so I checked the codes which are:
P1684 Driver 5 Line 4
P0123 Throttle Position (TP) Sensor Circuit High Voltage
I had the battery disconnected so I expected the 1684 but what about the 0123? Anyone else have similar issues?

I figured I'd check here as everyone has always been extremely helpful in the past and am thankful for this forum's search function. I also need to replace the multifunction switch as the fog lights like to come on and stay on all by themselves and don't know if this is a related issue or not. Any help would be greatly appreciated. Thanks folks.

[CREWZIN]

I did some checking on PT Do-It-Yourself.net and this is what it said:

I have a 2001 TE PT with 98k miles. The engine light came on and self tests reveal a P0123 fault code. I have tried to find pictures, diagrams, and easy to understand info on how to correct this code. The probable causes stated on the info from Auto Zone say the sensor open or shorted internally-replace component. Thanks. – Kathy, from Texas.

The P0123 fault code indicates: Throttle Position Sensor Voltage High - Throttle position sensor input above the maximum acceptable voltage.

The P0123 fault code is for the circuit, not the sensor. You can check the connector, however other causes include:

Throttle Position Sensor Sweep
Intermittent Condition
TP Signal Circuit Shorted To 5 Volt Supply Circuit
TP Signal Circuit Shorted To Battery Voltage
TP Sensor Internal Failure
TP Signal Circuit Open
Sensor Ground Circuit Open
PCM

Voltage and continuity measurements need to be performed. The power and ground circuits need to be verified. I admire your willingness to jump in with both feet, but unless you have experience with a voltmeter, DRB scan tool, diagnostic/service manuals, and familiarity with the electronic systems within the PT, you would be better served by seeing your local dealer for diagnostic help.


Now, personally, you had to take off the (UM) upper manifold to get to the thermostat. The UM is attached to the (TB) Throttle Body, So is the TPS (Throttle Position Sensor). It's located in back of the TB next to the IAC (Idle Air Controller) (See Haynes Manual you used for the thermostat). I suggest you take a good look at the TPS and IAC and see that you haven't dislodged any connections and make sure everything is tight. Check the clips to the wiring and all screws and bolts. I don't think the TPS would go bad just after the thermostat so check everything you touched, then, take off the negative battery terminal for 5 minutes (wiping out old codes) and see if the P0123 comes back. I don't think it will. Please let us know what you find.

P.S. The Multi-function switch should have nothing to do with your TPS problem.

[EDGEFIND]

Thanks for the info, I really appreciate it. I'll be able to look into it tomorrow. I'll keep you informed. I'm hoping it's something simple.

[Hooligan]

What codes did you throw before you changed the thermostat?

[EDGEFIND]

There weren't any before, just a puddle of coolant running down from the thermostat which my wife is now telling me has been going on for a while which I'm not happy about. She "says" she watched the temp gauge and kept the coolant levels up but I'm betting it was all reactionary to high temps. I'm probably way off on that issue as well with my luck. I just figured it was the cheapest fixable option at the time and an instant visual. I'm open and willing to look at any and all possible options right now though.

[slartyblarfast]

Voltage high means open circuit. I would bet a dollar that the tps is either not plugged in or not fully plugged in. TPS is on the throttle shaft on the other side from where the cable goes.

[CREWZIN]

Originally Posted by slartyblarfast

Voltage high means open circuit. I would bet a dollar that the tps is either not plugged in or not fully plugged in. TPS is on the throttle shaft on the other side from where the cable goes.

Sounds good to me. I think I mentioned that in my reply.

[EDGEFIND]

Originally Posted by slartyblarfast

Voltage high means open circuit. I would bet a dollar that the tps is either not plugged in or not fully plugged in. TPS is on the throttle shaft on the other side from where the cable goes.

DING, DING, DING, DING, DING - If I had a dollar it'd be yours. Sure enough I was so worried about making sure the other plugs were properly locked with their secondary tabs that I didn't pay much attention to the simple one. It just wasn't clicked tight enough. I feel like a dumbass, but at least it's right now.

Now I'm concerned about the tightness of the bolts on the thermostat cover. The new o-ring was pretty rigid but I hate wrenching down bolts over plastic and I don't have a small torque wrench at the moment to make sure I have the proper setting. I'll have to give it a test run first to check for leaks and get it up to temp unless there is a better procedure someone has to offer.


Thanks again everyone. I really, really appreciate it. You're all good in my book.