TTAC commentator SonWon writes:
Hi Sajeev, this is part two of my Monte Carlo saga discussed in an older Piston Slap. I finally had the transmission codes read on my Monte Carlo. Just to remind everyone it is a 2000 with 196,000 miles, engine is a V6 3800, series 2. The transmission lost overdrive. It shifts fine through first, second, and third. The transmission shop said there are no codes and it must be a mechanical failure. They also said it could last a long time or fail very soon. So far there no strange noises except a small faint whine at 70 MPH. So I am actually asking about the engine codes. P0128, coolant thermostat (I know how to fix this); P0440, evap emissions system fault; P0463, fuel level sensor (i can live with this); P0481, fan control 2/3 circuit; P1115, ECT circuit intermittent voltage high. So there is my list: what to fix? Oh, I should add the car runs okay.
Sajeev replies:
Nice to hear the Monte is still running after almost five months of use! I kinda thought it’d be recycled into Wal-Mart grade cookware by now.
Now to your stored engine codes, and something I thought I’d never say: don’t touch a damn thing. But that’s if you the state’s emissions test, the car runs safely (no overheating, etc) and the MPGs are reasonable for the car’s rather precarious (i.e. high miles, no overdrive gear) mechanical condition. If the car fails inspection, fixing the codes relating to your evaporative emissions and coolant temperature are the first place to look. Judging by a quick Google search, there’s a remote chance that replacing the thermostat will take out more than one of these codes.
Drive this car into the ground and save your money. Or perhaps piss it away when you pity your dead Monte Carlo and want to bring it back to life. Either way, enjoy the good times while you can.
[Send your queries to mehta@ttac.com]
Don’t touch anything!
A coolant thermostat problem may be preventing the torque converter from locking up… Most modern cars have higher upshift points and may disable TC lockup until the car warms up to make the car warm up faster in the winter.
Did the transmission shop drop the pan and examine the fluid? If so, did they find anything unusual? Is it possible that the shifter is dropping the transmission into D3 rather than D4?
If the car is otherwise in good mechanical condition, and you like it, I don’t see a problem with spending money on a single large repair like the transmission. You always run the risk that the car will be stolen/totalled/incur another major repair in the near future, but I think on the average you’d come out ahead.
If P0128 means that the thermostat is no good, that’s an easy fix. P0440 could just be a loose or failing fuel filler cap. If your Monte has the kind of cap that just clicks into place rather than threading in it might be likely that the cap just isn’t seated properly. My 2004 Buick Century has that kind of filler cap, and it’s easy to think it’s properly seated when it’s not. As the 2001 Monte is also a W-body it might use the same style cap.
10 years old, 200k miles…your car is in full beater mode now and not worth really investing in further. Change your thermostat, maybe. Otherwise, take it out to an empty field and have fun doing donuts in the mud…you’ve gotten your money’s worth on that car and have nothing to lose now
oh yeah…and i can tell you from personal high mileage beater GM experience…despite all those codes, this thing could keep running for a long time without you ever doing anything about them
Your car is basically a hospice patient. A tank of gas will double it’s value but not necessarily it’s range. Would limit it’s use to in-town destinations and keep a screwdriver in the glove compartment to remove license plate and other identifying tags once it does go.Might consider filing down VIN numbers now.
P0440 is a general evap system leak. It’s not a big deal if you never find and fix the problem. Like stated earlier though, try another gas cap. Sometimes it seems to fix the problem. Otherwise, check all your evap hoses, that you can see, and look for dry-rot, cracks, etc.
P1115 and P0128 may be related. The “circuit voltage high intermittent” fault, for the engine coolant temp (ECT) sensor, could mean a faulty coolant temp sensor. Before you replace the sensor, check the circuit and make sure the connector is still fine and there is no loose wires from any kind of stress (engine movement, etc.). “Circuit high” is an indicator of an electrical connection coming loose and the connection is not complete, or the circuit is open.
Like stated earlier, the powertrain conrol module (PCM), which monitors engine coolant temp and uses the input for things like transmission shit strategies, may not be allowing the transmission to shift into overdrive based on the (faulty)input from the ECT sensor. So there is a possibilty that it is trying to protect the engine from overheat issues by essentially limiting vehicle speed by keeping you from going into 4th gear.
Start with the cheap basics first though. Do a basic transmisson tune-up (fitler and fluid) and replace the thermostat. Also do a coolant fluch and fill to be on the safe side. Have the codes cleared and see what, if any, comes back after a test drive. From that point, if any codes return, I would check the electrical points I mentioend earlier.
I hope this helps :)
Also…
I forgot to mention that the GM 4-speed autos are generally a reliable, high-mileage, transmission (way better than Chrysler’s – ughh…). But, there is the slight possibility that it could be a bad solenoid in the transmission. Normally, it should show a code for that, but it is plausible. The shift solenoids, relatively speaking, are easy to replace too if that’s the problem.
Good luck again :)
EJECT EJECT EJECT
I’d try a few of the fixes mentioned and keep expense less than $100 and see what results are then drive it until major repair. Do it yourself as much as possible. Check your library for a Chilton’s book. Beware of spending a little to fix this and a little to fix that which eventually gets you over $500 and still no 4th gear.
Welcome to the world on the other end of the odometer! This is where the clean fingernail reliability “experts” get weeded out. I would suggest ignoring the evap issues if it is a problem beyond the cap. Checking for these kind of leaks may be difficult and time consuming. You don’t want to pay an pro $100 an hour to chase leaks. However, there are a few areas in these systems that are typically the weak links and you can try to address them if you are inclined to have a zero code ECU. Signing up for ALLDATADIY is very helpful. If you have a state inspection that requires the light to be off, fill the tank completely and reset the computer, then go to the testing center. Evaporative leakdown tests do not run under full tank conditions. Of course, the car needs to know the tank is full, something that your car can’t tell at the moment with the fuel sensor issue.
Fix the coolant temperature related issues. Without proper temperature readings, the ECM is no doubt substituting default values for real data. That kills mileage, performance, and raises the chance for an emissions related failure. Autojuunkie’s post on the coolant issue is correct.
You should be able to get the car running at the right temperature yourself for a small amount of money and some time. It is worth the fix because this drivetrain will outlast the body of the car. 3800’s are today’s slant six (well, mostly). No disrespect meant to Autojunkie on the transmission advice, but if you have not changed the trans fluid in years, don’t start now. The clean fluid may cause slippage to start in high mileage transmissions.
How important that OD fourth gear is depends on your driving. If you are a short tripper, don’t worry about it. However, if you spend 50% of your time on the highway commuting 50 miles a day, the higher RPM’s will kill your economy.
Good luck! There’s no reason to abandon this car if you can fix it for small money and the body is good.
yes you need to fix the fan and ECT issues. If the thing is on the edge of overheating becaust the fans are not working properly the transmission shift schedules will be screwed. Not to mention the transmission is probably being cooked because the transmission cooler is in the radiator.