Hi all,

I need some help! I'm a little bit stumped here.

My Sportage has an electrical radiator fan and the SPAL fan-pwm v3 controller. It is hooked up to the stock temperature sensor, the one used for the dashboard temp gauge, not the one the computer uses. I am thinking of changing that. Anyway...

The problem I'm having is it keeps throwing the P0128 code. This code means the engine took to long to warm up to operating temperature.

I thought my thermostat was the problem, but I have changed it a couple times now. One time it was upside-down and I thought that was the problem, but when I put it back the right way, the problem didn't go away.

I use the higher temperature thermostat. Autozone usually lists 2 thermostats for this vehicle, and I pick the hotter one. Still doesn't help.

Maybe my radiator fan is turning on too early. But I don't see how this would stop the engine from warming up. The thermostat should be closed when the engine isn't warmed up, so it shouldn't matter how cold the radiator water is, should it? Plus, what if I lived in a cold climate? The radiator water would be cold anyway.

Plus, I don't see how the fan could be the problem, because when I'm driving down the road, there will be more airflow through the radiator than the fan can supply! So if too much airflow on the radiator was the problem, the engine wouldn't be able to warm up just from driving down the road!

Anyway, so I'm puzzled. Any ideas? What else could it be?

Nuke,
Sounds to me like you may have a water temp sensor problem (the one on the drivers side of the thermostat housing) if everything you checked is ok. Let us know what you find.

Everet <img src="/forums/images/graemlins/patriot.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" />

Maybe, but I have an OBDII scan tool that plugs into my laptop and I can monitor the temperature values coming from that temp sensor, and they seem correct, so I don't think there is anything wrong with the sensor.

One thing I did notice is that the system voltages in my car are lower than they should be. Measured at the alternator output, I see 14 volts, but measured at the battery, I only see 13 volts with the engine running, then measured at the cigarette lighter I see about 12.5 volts. I figure it's crappy wiring in the vehicle, and I plan on upgrading the wiring, unless the alternator is going bad.

Hey, just a thought, last time I changed out the water pump, I installed one that said it was a high-flow water pump, it was supposed to flow better than the stock water pump.

Do y'all think maybe this high flow water pump could be causing the problem?

Well mystery solved. I could have SWORN that I didn't, but last time I changed the thermostat, I put a fail-safe one in there. I had a problem with my fan and the engine overheated a little, so the thermostat was locked open. So, that's why.

Also, it turns out my radiator has had a slow leak for a long time and was low on water. It just sprang a leak somewhere for no apparent reason. It's an aftermarket all-metal radiator (brass I think or bronze or whatever they use). Well, luckily I still had the old aluminum radiator which had nothing wrong with it lol... I swapped it back in. I also changed how my SPAL fan-pwm v3 electric fan controller was wired up... Instead of using the temperature gauge sending unit to get the temperature reading, I switched it so that it uses the sensor that the ECU reads. That way I can tune when the fan goes on to be more in tune with the ECU's readings. I found that the temp gauge sending unit's readings didn't coincide very well with the readings from the temp sensor the ECU uses.

Everything's working great now!