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2001 VW Beetle Coolant Temp Sensor

Awhile back my check engine light came on and I was told that my coolant temp sensor needs to be replaced. That it wasn’t an emergency but to get to it before to long and to be honest I just forgot/ignored it.

Well now when it is cold outside my car has difficulty starting. It pauses a few seconds before starting and then runs a high rpm until the car warms up and then drives just fine. So I am wondering if the two problems are linked?

If so how difficult is a coolant temp sensor to replace? Is it as easy as pulling the old one out and putting the new one in? Or is it tricky in which case I should take it to a mechanic? I just hate to pay almost $100 if it is something I can do myself for the cost of the part.

Also, should I get the part from a VW dealership parts department or is a different brand from a general auto parts store ok?

A coolant temp sensor failure (if it was the sensor,I find more often it is a poor connection or a wiring issue) should not be ignored,it causes the car to run rich all the time,causing poor mileage,reduces the time between oil changes,and can lead to catalytic converter failure.

I don’t know the exact location on your car but they are usually near the upper radiator hose outlet or in the intake manifold(where they can contact coolant) the difficulty will be in getting the wire harness disconnected(some kind of retainer involved) and having a socket deep enough to fit. Make sure you are removing the sensor for the engine management not for the temp gague.

I see no reason to require you to install a Dealer part,can you find the part elsewhere?

As I recall the part is about $15.00 and it take about five minutes when you know how to do it. It may be a little tight getting your fingers in there however.

You might as well get the part from VW they are cheap and they should have them in stock.

Yes, the starting problem is probably related to the failed coolant temperature sensor. You should have replace it when the Check Engine Light came on.

Coolant temp sensors are not difficult to replace, but there may be more than one. There may a sensor that feeds a signal to to the computer, a sensor that feeds a signal to the dashboard gauge, and a sensor in the radiator that controls the cooling fan(s).

You need to figure out which coolant temp sensor feeds the computer. That’s the one that’s causing your problems.

You take the old one out and put the new one in. Then you may have to bleed air out of the cooling system and refill the radiator if any coolant was lost.

You should restate the symptoms. “It pauses a few seconds before starting…” means what? That you turn the ignition key to START, and absolutely nothing happens, or, what?
When the engine starts, it “…runs at high rpm…” to what rpm, and for how long?
You got answers, we got answers.

When I turn the ignition key to start it cranks for a few seconds and then starts up versus starting right up like it usually does. Then it occasionally runs at a high RPM meaning. 3000 rpm versus the usual 800. When this happens it usually only last 30 seconds to a minute, or until the car warms up a bit.

Faulty coolant temp sensors are very common on 4 cylinder VWs of this age. If the check engine light was on and the error code was to the effect of “coolant temp sensor resistance too high” then the sensor is at fault. It’s a simple repair that can be done with any aftermarket one you can find.

You can usually get the new one in without draining the system, but put a catch pan under the car because you will spill a little bit. Just top it off after the repair is done.