What should I be looking for with code P0442 2.5 liter V6, auto, 4WD

p0016
P0016 OBD II Trouble Code Camshaft Position Camshaft Position Correlation...
p0128
P0128 OBD II Trouble Code Coolant Thermostat Coolant Temperature Below...
p0206
P0206 OBD II Trouble Code Injector Circuit Malfunction Cylinder 6...
p0306

P0306 OBD II Trouble Code Cylinder 6 Misfire Detected

p0436

P0463 OBD II Trouble Code Fuel Level Sensor Circuit High Input...

As you have determined, the P0128 code is related to a low coolant temperature.

This can be one or two issues - the thermostat or the temperature sensor itself. If you're confident that the thermostat was properly replaced - you should probably look into the temperature senor itself.

Here's a video about the P0128 code diagnosing process.

1,2,3 are across the back under the intake and4,5,6 are across the front

I did a quick Google search and found P0128 may indicate a stuck thermostat. The engine is not warming up properly. There are other causes: A code P0128 may mean that one or more of the following has happened:
* Low engine coolant level
* Leaking or stuck open thermostat
* Faulty cooling fan (running too much)
* Faulty coolant temperature (ECT) sensor
* Faulty intake air temperature (IAT) sensor
I got most this info from another thread on Fixya. I hope that it helps you.

I'm having the exact same codes on my '01 GT. http://www.club3g.com/forum/problem-reports/112664-p0403-exhaust-gas-recirculation-circuit-malfunction.html

check out the last post on that page. literally just got done getting the "BB" out of the tubing. haven't found out if it solved that problem yet, but I'm hoping to not have to change the solenoid.

I'm still working on the P0128

P0128 is the fault code to check 1.the coolant level 2. thermostat defective 3. ECT (engine coolant temperature) sensor defective

Hi, you have a faulty thermostat, so you should just need a thermostat, associated gasket (or gasket maker), and some fresh antifreeze. Consult a vehicle-specific manual for specifics on your particular engine.

More P0128 info @ http://www.obd-codes.com/p0128

2000 TOYOTA TACOMA 2.7L 4-cyl Engine Code 3RZ-FE

Engine Oil Grade 1......API* All TEMPS......5W-30 Optional ..10W-30
Engine, 2WD, with filter..........5.5 liters
Engine, 4WD, with filter..........5.4 liters

Manual Transmission,......GL-5/ GL-4 All TEMPS......75W-90
Automatic Transmission,A340E......AF3 / A43D......AF3

Differential, Front/ Rear W/ ADRD......GL-5 ALL TEMPS......75W-90
Differential, Front Less ADRD......GL-5 ALL TEMPS......80W-90

Transfer Case,......GL-4/GL-5 ALL TEMPS......75W-90 Gear oil.

Capacity:
Cooling System, Initial Fill..........8.5 liters
Automatic Transmission, A340E Initial Fill..........1.6 liters
Automatic Transmission, A340F Initial Fill..........2 liters
Automatic Transmission, A43D Initial Fill..........2.4 liters
Automatic Transmission, Total Fill
4 speed A340E..........7.2 liters
4 speed A340F..........10.1 liters
4 speed A43D..........6.5 liters
Manual Transmission, ..........2.5 liters
Differential, With ADRD Front..........1.2 liters
Differential, Without ADRD Front..........1.1 liters
Differential, 2WD V6 Rear..........2.6 liters
Differential, 4WD Extra Long Rear..........2.5 liters
Differential, Short WB With LSD Rear..........2.7 liters
Differential, Short WB Without LS Rear..........2.6 liters
Transfer Case, Electronic..........1.2 liters
Transfer Case, STD..........1 liters

Replacing it is the only fix. Sounds like it may be sticking open slightly.

PO172 means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). I would replace the thermostat first. The computer could be injecting too much fuel because it thinks it never gets to operating temperature. That may keep the light off.