p0128

Long story short, I got the car up to 80MPH on the freeway to pass a car. CEL came on, stopped at autozone, came up with p0128. I keep geting different answers, on what caused it. Does anyone know what really could cause this, and how much to expect to shell out at the dealer?
2002 Impala 3.8
edit....
Onstar was completely useless... Could've saved myself $215.00

P0128 Engine Coolant Temp below regulating Temperature. This can mean that your thermostat is stuck open. What is your engine temp guage doing during normal driving?
If the thermostat is stuck open, your engine will never get warm, causing reduced gas mileage, and you won't get good heater performance.
The thermostat on the 3.8 is easy to change, and you can get one at any autoparts store for about $10.

Another cause could be a bad temperature sensor. This is not as easy, but you can still do it yourself in the driveway. I don't know how much the sensors cost, but again, autozone should have them.

I have also heard of a leak in the coolant system causing this code. Is the radiator full, and have you seen any signs of a leak?

Your local mechanic could handle this if you don't want to pay a lot at the dealer. It doesn't sound like a big problem.

P0128 Engine Coolant Temp below regulating Temperature. This can mean that your thermostat is stuck open. What is your engine temp guage doing during normal driving?
If the thermostat is stuck open, your engine will never get warm, causing reduced gas mileage, and you won't get good heater performance.
The thermostat on the 3.8 is easy to change, and you can get one at any autoparts store for about $10.

Another cause could be a bad temperature sensor. This is not as easy, but you can still do it yourself in the driveway. I don't know how much the sensors cost, but again, autozone should have them.

I have also heard of a leak in the coolant system causing this code. Is the radiator full, and have you seen any signs of a leak?

Your local mechanic could handle this if you don't want to pay a lot at the dealer. It doesn't sound like a big problem.


Well, I did find it kinda odd that i only got about 200 miles out of a full tank of gas. Temp gauge reads normal when idle, but when moving, temp drops a lot... this started right after I got a flush n fill, about 5 months ago. but the heater does get hot, and stays hot. Checked radiator, and its full. No milky substance in oil. but I guess i'll find out what the problem is come monday.....

Was the thermostat replaced when you got the flush and fill? It should have been.
Given what's happening with your temp guage, I'd say it's 90% sure you have a stuck thermostat. That's good, because it's an easy fix.
My 3.8 Impala gets 310-325 miles per tank, 60% city, 40% highway driving.
Check your air filter and tire pressures, they have an effect on mileage.

Was the thermostat replaced when you got the flush and fill? It should have been.
Given what's happening with your temp guage, I'd say it's 90% sure you have a stuck thermostat. That's good, because it's an easy fix.
My 3.8 Impala gets 310-325 miles per tank, 60% city, 40% highway driving.
Check your air filter and tire pressures, they have an effect on mileage.
Well, they didn't replace the t-stat, I got the work done at Fast Eddies (never again.) I did just swap out my stock wheels/tires for 18's; 30 PSI all the way around. I got a K&N filter, and its ok. If its the tires, i'll swap those bad boys out real quick! Gas in my area is running about 3.38/gal. Can't afford to fill up every 3 days.

I have heard the larger rims will reduce mileage a little, but I've got the stock 16s so I don't have personal experience with it.
If your fuel filter hasn't been changed in the last 50-60K miles, you might get that done (20 minute job, filter $10 or so at autozone, no special tools). A clogged filter can hurt the mileage a little, too.
The winter gas also reduces mileage about 5-10%.
The biggest factor in gas mileage is driving style. Fast starts, hard acceleration, not coasting up to stop lights, lots of high speed driving, lots of in town driving, all hurt your mileage.

I have heard the larger rims will reduce mileage a little, but I've got the stock 16s so I don't have personal experience with it.
If your fuel filter hasn't been changed in the last 50-60K miles, you might get that done (20 minute job, filter $10 or so at autozone, no special tools). A clogged filter can hurt the mileage a little, too.
The winter gas also reduces mileage about 5-10%.
The biggest factor in gas mileage is driving style. Fast starts, hard acceleration, not coasting up to stop lights, lots of high speed driving, lots of in town driving, all hurt your mileage.
Well, the dealer called.... It is the thermostat... Not bad, simple fix... Until they said that I need the following things fixed...
1.LIM gasket (leaking oil, and coolant)
2.Rocker gasket (leaking oil)
3.Power steering seal (i think). I knew it was leaking.
4.left wheel bearing (the guy said that they were loose)
now this $161.00 repair is now going to cost me (drum roll please......)
$1,453.42! thats not even including the rental car i've had since saturday.
This car only has 63,000 miles on it, and already i'm having to deal with major repairs:banghead:
I think I would've been better off keeping my Grand Am.

I would have them fix the thermostat and take the car to another mechanic for a second opinion on everything else.
Wheel bearings are a fairly common problem area on our cars. Unless you have noise or an ABS/Trac Off light, I might leave that alone for a while. The new bearing should cost less than $200, but installation takes a while I think.
LIM gasket is another common problem. The dealer will charge you a lot more than an independent shop of that repair also. If you have no oil in the antifreeze, and no antifreeze in the oil, you might be okay to let that go until you can save up for the repair. It just depends on how bad it's leaking. Some people have been successful in getting GM to pay for LIM repairs, because the problem is so widespread. I would push them hard for warranty consideration, especially since you have so few miles on your car.
Power steering, I might just keep adding fluid if the leak isn't very bad. Again, it will be cheaper to get that fixed somewhere else.
As you can tell, I'm not a big fan of dealer maintenance. In my experience, it's always much more expensive than an independent shop, and usually not as well done.
Let us know how things work out!

I would have them fix the thermostat and take the car to another mechanic for a second opinion on everything else.
Wheel bearings are a fairly common problem area on our cars. Unless you have noise or an ABS/Trac Off light, I might leave that alone for a while. The new bearing should cost less than $200, but installation takes a while I think.
LIM gasket is another common problem. The dealer will charge you a lot more than an independent shop of that repair also. If you have no oil in the antifreeze, and no antifreeze in the oil, you might be okay to let that go until you can save up for the repair. It just depends on how bad it's leaking. Some people have been successful in getting GM to pay for LIM repairs, because the problem is so widespread. I would push them hard for warranty consideration, especially since you have so few miles on your car.
Power steering, I might just keep adding fluid if the leak isn't very bad. Again, it will be cheaper to get that fixed somewhere else.
As you can tell, I'm not a big fan of dealer maintenance. In my experience, it's always much more expensive than an independent shop, and usually not as well done.
Let us know how things work out!

Well, 4 days, and $1,600.00 later, i finally got my car back. The steering issue is fixed, it doesnt bind up anymore, but now my question is: Is it normal to smell something like rubber burning for a while? the dealer said that everything is ok, but the smell is questionable. Any ideas?

I would check carefully for any fluids leaking onto the exhaust. they may have just spilled something, or maybe there really is a leak. If it continues to smell after driving a few hours, I'd have them look at it.

Well, you already got it fixed....I see you paid $161 for the thermostat replacement. It's a 5 dollar part at Autozone and you can swap it out in 10 minutes if you are mildly mechanical. Just for future reference incase you have another one go bad cuz they do sometimes. Wheel bearings are also not that bad if you can do a brake job. I had to replace 3 of mine because they started to howl (almost sounds like studded tires).