Is there a Radiator fan switch screwed into the cooling system somewhere or does the ecm control the fans?

"code P0128 which indicated my Coolant Temperature Below Thermostat Regulating Temperature" Have you changed the thermostat or checked yours in hot water. It might be passing causing the engine to heat up. 221 is the trip point, they are operating normally. One sensor is the ECT that feeds the PCM, engine temp for fuel calculations and operates the fans. The other sensor is for the gauge or indicator light which ever the vehicle has.

JS08016.....I installed a Wells part which in my experience has always been a good product... After replacing the coolant temp sensor I no longer have the PO128... It doesn't have a blown head gasket. YET lol... It keeps running hot it may end up with one. Yetilikesbeer.... The code PO128 basically states that the vehicle is running "Below" the thermostat regulating temperature and is a strong indication the coolant temp sensor has failed. It is not sending a signal to the PCM setting the code... I replaced it and no longer have the code, however It continues to run hot in bumper to bumper traffic. Thanks guys, I appreciate the input.

I will also add that I have now replaced the Coolant temp sensor, Water Pump, Serp bent and Radiator cap... The Radiator looks very good and the car has always had Dexcool in it since it was new... I am going out to replace the thermostat now.

For warm up and highway traffic the coolant can be cooled by the rad as it passes through the faulty thermostat. As you hit heavy loads, high ambient temps or stop and go traffic the constant flow of passing fluid slowly heats up the entire coolant system. The rad is most efficent when the thermostat opens/closes allowing the stationary fluid to cool in the core, not just blast through. Trust me, I've had enough passing thermostats to know what happens, I'm to the point were I will not install the POS's untill I cycle them in a pot of water and confirm they open and close properly. For the code, there are multiple triggers in the ECU to trigger the code, there is most likely a runtime condition based on temp and running conditions to trigger it. I'm not bored enough to scroll through the code but I'm sure it's there. BTW If the fans triggered at the same time with the old ECT and the new one they are both good.

Test it in a pot of water. I pop them a few times then set them upside down and put water on the beast. If it drips toss it (a drip at 0 pressure is a spray at 12 ish). If it holds water it should be good.

I bought a 2005 Buick Rendezvous, the mechanic has changed the radiator, the water pump, the thermostat, the temp switch and it's still running hot...Help!!!!

What is your definition of HOT....they want the engine to run hot, the emit less pollutants. Most GM cars have two fans, one come on when the engine gets up to temp, the second one come on when you turn on the a/c.....in most cases they are wired so they are only running at 1/2 speed until the engine gets pretty hot....like in stop and go traffic...then around 230 degrees the fans get switched to high. You first need to determine how hot the engine is getting, are you loosing coolant? Then determine if both fans are working. Then notice their speed before the engine gets hot and after you think it is hot....are they running at two different speeds. Once you get all those answers you should know what to do next.

I to have a 2005 that stays over heating . Changed radiator cap thermostat new cooliant and bleed air out still overheats need help have a baby to drive around...

i got the same problem. im thinking new fans

By putting 12V directly to each fan you can verify that the fans are OK. You might check for a bad relay...owners manual might identify it and where it is...probably in the engine compartment and there is usually a chart on the inside of the cover identifying each relay. On most cars all the relays are the same so you can switch a couple of relays and if the problem goes with the relay you have found the problem.

This car is a piece of shit it overheats in traffic and even driving on the streets gm engineers did a horrible job in designing it it needs to be modified to be able to cool down im thinking add a air intake like setup on ghe hole by were the batery is and adding some sort of fan by the engine and another exit hole on. The oppisite side if anyone can think of how to be able to do it it would help everuone that owns thia veicle

I have a similar problem with my 06 Buick Rendezvous with 3.5L. I flushed the radiator and bled after refilling, replaced the thermostat and radiator cap, checked fuses and relays...all good. Now the car runs at just above 1/4 on the gauge but everyone now and then it spikes the needle to FULL OVERHEAT! I'll shut the car down and wait about an hour, start the car and all is good again - like nothing ever happened! I bought a new coolant temperature sensor but am having trouble locating where it goes. Do I need to remove the throttle body to get at it?

Is there any way to lower the trigger temp so my fan kicks on at a lower temp?

This a common problem for the Rendezvous. Try installing an adjustable fan controller. https://www.carid.com/images/hayden/pdf/performance-cooling-products-brochure-flyer.pdf

I also own a 2003 rendenvous an ir to was running hot i watched the reserve water tank and noticed it was blowing bubbles in it toke the engine apart because its true these engines had a faulty head and intake manifold gasket that goes out at about 150,000 miles replaced both gasket put all fluids back perged air and got a lower opening thermostat and and replaced the water temp sensor and now it runs at 195 degrees been driving on it for 2 years no problems and if you have the know how to rebuild the engine it will only cost you about 350.00 to rebuild and put all fluid back it not then your looking at anywhere from 1100.00 to 2500.00 if you have to have a shop replace it almost forgot to tell the most important thing shave the heads down i did mine the old school way but any good machine shop will do it for you for 150 to 225 price wise

I out toggle switch to control ac blower and all the running hot while in traffic stopped it was because fans were only working part time onworking

My 04 rendezvous has same problem so I ran a lighted switch directly to the fan relay to manually turn on,just don't forget to turn it off when you park car ,that's why I use the lighted switch,if you need fan to run at different speed,move wiring over to other relay.

I ran a lighted switch to manually turn on fan directly to the relay,just don't forget to turn off.if you need faster speed just move wiring over to other relay,there are 3,,low,med,high.

07 would overheat when sitting in traffic . Replaced rad and cap, water pump and thermostat . Flush out and replace with green anti freeze . It’s been running for 3 years and I would rather replace anti freeze every two years than a head or intake gasket .

I jave 02 3.4 an it gets hot when i turn ac on any help?