Where is thermostat on 97 VW Jetta 2,0L /engine runs cool/160 degrees

It can still overheat because the radiator may be plugged and not capable of removing heat. Without a thermostat, the engine mill most likely have difficulty reaching the correct operating temperature and run cool, which will cause the engine to run rich and waste gas.

dodges run like that. if your worried put a 180 degree thermostat in. maybe even a 160 . wont hurt engine or fuel mileage . my 99 dodge ram 1500 sport runs fine with 160 degree one. hope it helped , good luck

Looked at all of your codes. The #3 misfire can be due to losing the signal from the camshaft sensor. The temperature sensor could be critical because you said that when you hit 190 degreeF, that the engine performed better.

Sometimes depending on how you test a part, it will not duplicate the actual running conditions of the engine. For instance, the components that you test at room temperature of 70 degrees versus the 190 degrees making the electronics switch properly. The Cam sensor skipping the count on a running engine versus a continuity check on a bench.
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During some of the inspection, you may have unplugged a connector which cleaned it off. Now the contacts work and eliminated the problem.
This masked the problem, but just pulling the connector apart solved the problem.

Now for the higher RPM pattern, you are getting more cooling from the air than from water. The water sensor could be ineffective as there is sometimes a range of operation versus a dead-on mark.

The cheapest parts like the thermostat and water sensor could be candidates for replacement. The misfire could be a fluke were it not for the code of the camshaft sensor. Good luck on this

Hi Ken You seem to have two faults with your vehicle. One will be a speed sensor and the other possibly a bad connection. Take the vehicle for a diagnostic scan and pin point the problems (which the scan will do) and then sort them out. Regards John

sound like thermostat sticking close.replace thermostat and radiator pressure cap.if already done.you could have faulty water pump.if engine overheating at long slow traffic line or setting at a stand still.the engine cooling fans should be running, check and see if cooling fans running if not,check cooling fans fuses and relays.if all is good,hot wire make sure coolings fans okay.if all is good,code scan vechicle for faulty engine coolant temperature sensor and ecm problems.you need a code scanner where you can check live data check see if coolant temperature sensor reading correctly if engine coolant temperature is 190 degrees the coolant sensor. the scanner suppose to show 190 degrees in temperature if not it reads 80 or 90 degrees the engine coolant temperature sensor is faulty need replacing.if all is good check engine oil if look like milk shake blow head gasket will cause over heating.to be on the safe side i would replace thermostat and radiator pressure cap first.to make sure engine coolant circulating through radiator and engine block.

Heed of antifreeze coolant temperature!!!
First time you might check the thermostat operating.
The thermostat location for VW Jetta 1.9 TDI - AJM engine, is on back of the alternator at the bottom side of the bracket.
IMPORTANT: It is NOT necessary to replace the alternator if you want to change the thermostat !!!
Thermostat checking:
1. Cold engine. Start up the engine and watch of the water temp indicator. After first value 60 Celsius Degree you still warm up the engine until the lifter (pointer) reach 80 C deg. (second mark after 60 C deg.). At this time you let engine running at idle speed and check with your hand the thermostat plastic housing and hose temperature in bottom left side of the engine. Heed of alternator driving belt and ventilator fan !!!
2. If the thermostat is good the hose must be cold until the water temp indicator reach almost 90 C deg.
3. The thermostat opening temperature is 87 C deg.
4. If the hose is already warm the thermostat is out of order.

Thermostat location, Part number: 044121113, in german - "Kuehlregle" (Price around $25):



Important note: Always replace the thermostat seal, position 7 in the above picture.

Please do rate my response. Thanks!

Did you burp the air out of the cooling system once you were done reassembling the car? If not, click my screenname, go to my tips and tricks, and follow the procedure I posted there.

check the relays for your fans and check you fuses for yourfans

Get another boyfriend! "Just kidding"! ok, this is what I mean about "leaving it to the experts". #1 Make sure there is enough coolant, Check for leaks. Install a coolant pressure tester and check for leaks. Fix whats leaking. #2 Make sure coolant fans are coming on, and specifically at 220 degrees. If not, check fuses. Jump the coolant fan to make sure it comes on. if it does, then you may have a bad relay, make sure relay is commanded on. At this point , you may need a wire schematic for the coolant fans and related parts.

if the coolant is full and all the air is bleed out of the cooling system make sure the cooling fans turn on if not then check the relays and fuses and wiring. and if thats ok then use a block tester to check for a combustion leak. you can get a block tester for a parts store you simply install it in place of the radiator cap and run the car the chemical in the block tester will change color from blue to yellow if there is a combustion leak.