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Discussion Starter · #1 ·
Hello! I was wondering if anyone knew what the Check Engine Code PO128 was for on my Kia 2001 Sportage. A friend told me it was the Thermostat and I just would rather be sure.

Also, if that IS what the code is for, does anyone have any idea how much the part costs and/or how difficult it is to put in. Should I let a friend do it or am I better off taking it to the dealer?

Thank you so much!
 

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Unless there was a change after 2000 (That's the last year my shop manual covers) DTC P0128 is an invalid code for the Sportage. Are you sure you posted the numbers correctly?
 

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Discussion Starter · #4 ·
I saw it on the readout and I took the numbers down. I could have made a mistake, of course, but I think I got them right. Is it possible that 2001 has codes the 2000 and newer didn't have?

Thank you both for answering so quickly. I appreciate it!
 

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It's possible but unlikely. I'm not aware of any changes to the diagnostic system from 1998 right to 2002. But I could be wrong.


Originally posted by whirlygurly@Feb 24 2005, 09:45 AM
I saw it on the readout and I took the numbers down. I could have made a mistake, of course, but I think I got them right. Is it possible that 2001 has codes the 2000 and newer didn't have?

Thank you both for answering so quickly. I appreciate it!
 

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Discussion Starter · #7 ·
Thank you both - I don't what the heck is wrong with me then?! I must have got the numbers wrong when I wrote them down.

Is the code for something to do with Thermostat or Temperature Regulating similar? Maybe I inverted the numbers?

Thanks Again!
 

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Hi to all,

My girlfriend's 2001 Kia Sportage EX 4X4, at 40000 miles, has the check engine light coming on and when I read the diagnostic trouble code with the scan tool, the display says, 'P0128'.

According to the scan tool's manual, P0128 is a generic trouble code. The description is, "coolant thermostat (coolant temperature below thermostat regulating temperature)".

The dashboard temperature gauge indicates normal operating temperature. It is starting to cool off here in Pennsylvania yet she indicates heater output is fine on the cool mornings. Colder weather would provide a better test for the heater, and thus, the coolant temperature. I have erased P0128 a couple of times from her vehicle's on-board computer, yet it returns. Yesterday, on a highway ride, she turned her heater OFF (which, if anything, makes the engine run slightly warmer- less heat exchanger capacity with the heater off on most vehicles) and the check engine light came back on with the code P0128 stored on her car's PCM.

This vehicle doesn't appear to be suffering from 'coolant temperature below thermostat regulating temperature', i.e., a stuck-open thermostat.

It seems the coolant temperature sensor that provides the input to the vehicle's Powertrain Control Module (PCM, or on-board computer) is responding in an inappropriate manner. It could also be a problem with a connector, either at the sensor or at the PCM. Where is this sensor located?

What is needed is the complete diagnostic repair procedure for P0128. I had previously downloaded repair procedures on other DTCs stored in her PCM when the check engine light came on, without charge, from the Kia Motors website. I see now this information is available on a subscription basis. The readily available DTC service procedures came in handy for both myself and the dealer, in that we both knew what to expect at the time of the repair.

Her Sportage is still covered under the new car warranty, and the Service Manager at the dealership thinks it is a thermostat warranty repair, although he hasn't seen the car yet. The appointment at Sunbury Motors Kia is in exactly one week from today.

Your thoughts?

Doug
 

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I have a 2002 kia sportage and am having the same problem. The dealership cant seem to fix it seeing that they have had in the shop 10 times for the same code. They finally got kia involved who turned around and stated that there is no fix for the problem. They have changed what they could and even cleaned all the ground contacts. kia finally said that they have no idea how to fix it. I am once again taking it back to the shop(02/14/06), I have only owned the vehicle for 7 months. If anyone else is having the same problem let me know, I am documenting every case taht I come across.


Thanks Brian :liebe011:
 

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i am also having an issue with this on my '01 Sportage. it started right after the new year, with the check engine light coming on. i took it to auto zone, and they pulled the code P0128 COOLANT THERMOSTAT (COOLANT TEMPERATURE BELOW THERMOSTATREGULATING TEMPERATURE). They stated that this generally meant that the thermostat had failed and was stuck open, thereby not allowing the coolant to reach the correct temperature. i bought a new thermostat from them and replaced the old one. A couple of drives later, the check engine light came on again, so i took it back to auto zone and they pulled the same code. they stated that if the thermostat was new, it could be the sensor that failed. so i bought and installed the new sensor. no luck. it came back on again after a couple of drives. i finally took it to my local Dobbs and had them check it out. i got a phone call saying that they pulled the same code and they recommended that i replace my thermostat. i told them that the thermostat was less than a month old. the technician replied that there was nothing more he could tell me and that i should come pick up the vehicle. so here i am, a couple of months later, still throwing the same code, with no apparant fix. i guess the next step is to take it to kia, but there's no warranty, so i'm not holding out hope that they'll do anything about it either.
 

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For those that have mentioned they have replaced the ECT sensor, and that the Temp Gauge on the dash reads normally....

There are 2 temp sensors located at the thermostat housing for the DOHC 2.0L engine (98-01). There is one for the engine temp gauge on the dash panel and the other one is for the ECU/ECM. You can tell the difference by the wiring connector, the sensor for the dash panel only has 1 wire, the one for he ECU has 2 wires.

Some of this is generic and gleaned from other forums. The other thing I found interesting about this DTC P0128 is that it is a estimated or calculated based on ECT, IAT, MAF, vehicle speed and some others I think. The DTC is run once every drive cycle. If it fails in 2 drive cycles then the MIL (CEL) is illuminated. If it passed in 3 drive cycles the MIL (CEL) is turned off. There also is a time component to the calculations. If the coolant temp doesn't come up or respond with a rate of change in a specified time period, that can also set this DTC.

What is bad about this DTC is that it will not let the fuel system go into closed loop mode. The purpose of this DTC is to detect a faulty thermostat or a poorly performing ECT sensor. Since a cold running engine effects the emissions output this had to be checked. Funny (as in odd) that Kia did not published anything on this DTC in there books or on the GDS site.

Since ambient air temp based on the IAT sensor seems to play a part in the ECU calculations for this DTC, I would have a look at that sensor also. A scan tool would be invaluable here to see live temp data on the engine and intake air. If there was trouble with the MAF sensor your engine would be running very poorly in my opinion. So even though it has a roll in the ECU calculations, I might tend to discount that sensor being bad. The IAT sensor (intake air temp) is located on the top of the air filter housing, in the general area of the engine compartment diagnostic connector.

The cable harness that leads to the thermostat housing area for those temp sensors is not well protected in my opinion. I would be looking and inspecting the wires very closely for any nicks or cuts in the insulation. If that plastic sheathing has come off that protect the wire bundle, go to the auto-parts store and buy some and replace it.

I have never had this DTC code or error on any of my vehicles. Just offering this as some possible suggestions as to what to look for.

---------------------------------------------------------------
ECU - Engine Control Unit (or module)
ECT - Engine Coolant Temp
IAT - Intake Air Temp
MAF - Mass Air Flow
DTC - Diagnostic Trouble Code
MIL - Malfunction Indicator Lamp (also CEL check engine light)

:cool:
 

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Check Engine Light

Have you checked for a crack in the exhaust manifold?
I have a check engine light and this was the source of the light.
Car drives OK. Getting a quote fro a used manifold from a junk yard.
Kia parts are too expensive from the dealer.
 

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Ect

Hi all,

I had this same problem on my sportage a while back. took abour 10 trips to the dealer. YOu need to replace your thermostat housing. the one you currently have doesn't allow for the sensor to get into the water.
 

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P0128 code

been having the same problem. replaced the IAC sensor ($150), thermostat($35), and temperature sensor ($30). was good for maybe 3 days. This got rid of most of the codes but Pesky P0128 came back like your mother-in-laws fruit cake.

the problem was the rate of rise for the temperature. I got the thermostat from Kia 190 degree ($35), that didn't do it. I changed to another thermostat at 195 degrees, ok for a week. then one of the engineers where I work, said I went the wrong way, should have been a 180 degree thermostat, so the engine heats up faster,I said Eurika or something like that. I changed the thermostat, and Air temp sensor, it worked.

here are part numbers for 180 degree thermostats

Gates 334885 ($5)
Beck/Arnly 1430733
Stat 45868

I also changed the Air Charge Temperature sensor
Airtex 550154 ($35)
 

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ok, maybe this is premature, but I was wrong on the temperature, or I should say the engineer was wrong. I changed to the 180, lasted 2 days again. Got the AllData printout from my mechanic. here it is.

KMA has since received reports of DTC P0128. they found the production start dates change the thermostats, interchangability codes (ITC) and the ECM and thermostat "set" part numbers. Previous information in the 2001 parts catalog may have caused inadvertant use of incorrect parts.
ok here goes.
Determine if the vehicle falls in the production date range for THERMOSTAT MONITORING. Vehicles built before 09/18/00 (4DR) or built before 10/02/00(2DR) were NOT equipped with thermostat monitoring. If you have a Kia with a P0128 code built before those dates wrong parts may have been installed. Rather then chasing the other codes it will generate, first check the following.
2.Check installed thermostat and P/N. Vehicles built before 06/17/00 it should be equipped with thermostat P/N OK9FC15 171, KE5D3 15 171, or 0k01C 15 17Y. Vehicles built AFTER 06/17/00 should use P/N 0K013 15 171 or set P/N 0k01C 1517Y.
The earlier ones are distinguished by a secondary thermostatic valve on them, the newer ones have a little rivit floating in a hole on them, also the newer one is a 195 degree thermostat.
3. Check the Engine Control Module P/N on label on module. The P/N for the ECM without Thermostat Monitoring is: OK07A 18 1881 for both the 2dr and 4dr models. The P/N for ECM's with Thermostat Monitoring are: 39100 3X100 (4dr) and OK07A 18 1881A(2dr). use the right set with the right ECM. This is why the P0128 code pops up.

so you have to have the right thermostat with the right engine module. I also changed the intake air monitor sensor. Be sure to use a new gasket, as the gasket material also changed from paper to a rubber/paper type , add a little Permatex blue gel. seems to working now.

theres more;
The intake Air temperature rationality check (we all need one of those don't we) monitors the sensors circuit as well as informs the ECM weather the signal matches the expected value or range for the circumstances. For example if the IAT signal reads extremely high or low, the ECM would conclude that the signal is incorrect and would store a DTC PO111. The ECM can also determine the faulty sensor by comparing the IAT sensor signal to changes in coolant temperature over a certin period of time.

I only did this when I got the new information on Monday when I also found one of my coils was bad, and the valve cover gasket was leaking into the #2 cylinder coil. bit confusing, hope this helps.
 

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a week has gone by and 400 miles. all is working as it is supposed to. Think we got it this time. it was matching the module to the thermostat.
 

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Outstanding News and a great follow up "healixrider".

What you posted make the most since out of this issue with the P0128 codes. It sounds like you nip yours in the bud and I hope everyone else that has this problem can learn and apply what you have shared.

Great Job!!!
 

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PO128 2002 Kia Sportage

Got P0128 for 6mos on my 2002 Sportage (77Kmi). Drove me crazy. Replaced therm with Kia OEM ($30) twice with no luck. Also replaced temp & guage sensors. Still got code. Took to dealer who said they couldn't find anything & couldn't do anything. Finally accepted the idea that I may have been replacing bad parts with parts (a terrible thing to accept!!). Replaced therm again with Duralast 15869 (Autozone). NO CODES OF ANY KIND FOR THE LAST 6000 MILES. Might try it. Good Luck!!
 
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