# Coolant Temperature Sensor Resistance Values & Replacement



## chiltonRabbit (Feb 14, 2009)

I measured the resistance of my coolant temp sensor between terminals 1 and 3 and measured an open circuit. The chilton manual says the resistance should be around 1.5k to 2k ohms cold and about 275-375 ohms at 80C.









If I check the resistance from terminal 1 and the terminal above it (I'm guessing it's terminal 2) the resistance is:
1.386k ohms cold
175 ohms at 80C
Either way the resistance values are not within spec.
So the questions I have are:
1. Was terminal 1 and 3 the correct measurement to take?
2. When replacing the sensor and draining the coolant what is the proper way of disposing the coolant? (I live in California by the way)


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## germancarnut51 (Mar 23, 2008)

*Re: Coolant Temperature Sensor Resistance Values & Replacement (chiltonRabbit)*

Just replace the sensor. 
It only costs about $8 from europartsdirect.com. Order the o-ring seal ($1.70) at the same time. Check the rest of your car, and order the same checp stuff all at the same time, because you get free shipping on orders over $49.
You don't have to drain the coolant. Very little will leak out if you simply pull the sensor, stick your finger in the hole and run it around to get the much out so the o-ring can seal after you replace it, and stick the new sensor back in.
If you choose to drain the cooling system (time for a change), coolant is classified as a hazardous waste, and is very toxic. If/when you drain it, you have to capture it and locate a hazardous waste site that will accept it from you. Many cities have hazardous waste collection sites. Check with your city.


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## chiltonRabbit (Feb 14, 2009)

*Re: Coolant Temperature Sensor Resistance Values & Replacement (germancarnut51)*

Couldn't find it at autozone or europartsdirect.com.
I think http://www.tdiparts.com has them. The thing is I'm not sure which one.
My car has a *green rectangular* 4 prong sensor. The sensor at autozone was a green D-shaped 4 prong sensor. I'm thinking I need the blue 4 prong from tdiparts.com, but it doesn't list my engine (AEG) on the 'This Product Fits the Following Vehicles' list.


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## germancarnut51 (Mar 23, 2008)

*Re: Coolant Temperature Sensor Resistance Values & Replacement (chiltonRabbit)*

You were probably looking in the wrong place at europartsdirect.com.
I had no problem at all locating a green rectangular 4-pin temp sensor for a MKIV TDI engine.
manufacturer: Meyle part number: VWW004876 price: $14.25
Parts are not always listed under the category that you think they should be. To find your temp sensor, since you wrote that your engine is a AEG TDI, I assumed that you have a MKIV. Knowing that MKIVs were made between 99.5 and about 2004, I picked 2002 for the year of the car I was looking for parts for, and 2.0TDI as the engine.
Since I found the temp sensor for my MKIII under Instrument Sensor Heading, that's where I looked for yours. And BINGO, there it was, listed along with the Green D-shaped sensor that you wrote that you found.
Don't forget the sensor o-ring. Infact get a spare or two. They're cheap and there are more than one on your engine. If you can get your order up to $49, the shipping is free. Otherwise, I think the last small emergency order I placed (needed the parts right away, and didn't need $49 worth) cost me like $8 for shipping.
I make a list of small stuff I'd like to keep for spares when I'm between orders, and when I need a part now, I run the order total up to $49 from my list of desired spares. Some of the stuff that is handy to have (at least on MKIIIs) are for instance: The coolant flange on the back of the head (that houses the sensor you want to buy), sensor o-rings, and thermostat cover (they leak like the coolant flange). The stupid coolant flange probably costs $20-$25 at the VW dealer if you were forced to buy it there in an emergency (like $8.70 from europartsdirect). The thermostat cover costs like $4.70 from europartsdirect, and about $10 from VW. You get the picture? 


_Modified by germancarnut51 at 8:10 PM 2-26-2009_


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## chiltonRabbit (Feb 14, 2009)

*Re: Coolant Temperature Sensor Resistance Values & Replacement (germancarnut51)*

Thanks.
The VWW004876 sensor (D-shaped) is actually the wrong one for my car. I saw that one earlier but couldn't find a green *rectangular* coolant sensor. I checked again and found the one I was looking for. Didn't realize it was labeled as a water temperature sender. I was looking for it to say coolant sensor.
$13.26 - Meyle VWW090712 -- Water Temperature Sender
For Gauge & Fuel Injection; Blue 4 Pin, 20mm Clip-In 
Not to get too off topic but:
I might need a new ignition wire set but not sure the aftermarket one they have listed is any good. (part #: VWW081797). Any difference between this one and the ones from autozone.com?
I also just recently bought bosch platinum+4 spark plugs and have been reading mostly negative reviews about them (no problems this far). Should I grab NGK spark plugs instead? (part #: VWW038811)


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## germancarnut51 (Mar 23, 2008)

*Re: Coolant Temperature Sensor Resistance Values & Replacement (chiltonRabbit)*

I think that the recommended plug (and original equipment) is probably a Bosch Silver plug, and that is what I would probably stick to if I were you. I have also used a lot of Original Bosch Platinums, but that's on my older Non-OBDII cars. I recommend staying with the Car Manufacturer's OE Plug for all OBDII cars.
I have not bought NGK for decades, so I am not in a position to comment on what they are making now. But when I bought them before, they didn't last long.
In general, I don't buy any Parts Store Generic Parts. AutoZone and Kragen/Oreillys/PartsAmerica sell some OEM parts under their own labels, but many of the items they sell are junk parts made in Third World Countries. A good example of this are the house branded ignition caps and ignition rotors sold for VW MKIIIs. The parts are actually made in Italy by an unidentified manufacturer. Electrical contacts are aluminum (burns up rapidly, and is a poor condutor of electricity) instead of the brass used in Bosch, and the plastic is of an inferior quality, and molding (caps do not fit correctly).
If you are considering buying generic parts, I strongly suggest that you only buy parts made by Bosch or another German Company and inspect the parts carefully before buying.
Ignition Wires must have the Original German heavy metal ends, no matter what brand name is on the box or where they were made.
Avoid buying any parts made in China.


_Modified by germancarnut51 at 2:39 AM 2-27-2009_


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## 2low4fathoes (Apr 25, 2006)

*Re: Coolant Temperature Sensor Resistance Values & Replacement (germancarnut51)*

carquest, got it for under 3$. they get all factory parts for much less. just got a full ring rebuild for a 2.0 for under 30 there.


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