Water ThermoSenor Code

[beefmobile]

hey guys im back again and i threw a code: 9--Water Thermosensor.

the symptoms were at WOT, the engine would fall on its face and then pick up after a second. it also did this right after shifting gears. i threw a code once it warmed up, but it occasionally went off and then back on. i pulled the code and dont know where to start.

thx for your help in advance.

[Inodoro Pereyra]

If you're talking about the coolant temperature sensor, it's the one on the thermostat housing.
Follow the top radiator hose to the engine. Where it connects to the engine, you'll see the sensor right besides it.

[beefmobile]

then what, replace it?

[Inodoro Pereyra]

The proper way to do it would be to test it first, to make sure it's the sensor and not the connector/wires, but being it's a fairly cheap part (about $20) you could visually inspect the wiring and just have it replaced.

[beefmobile]

test it? like give it power and see if it does anything?

are the symptoms im having relate to the sensor?

and can the sensor actually be reading the correct numbers, and there be a real problem?

[Inodoro Pereyra]

You can actually test the sensor right on the engine.
With the engine cold, take a multimeter , set it on the Ohm (Ω) scale, disconnect the sensor connector and measure the resistance between the sensor's pins. It should read between 2000 and 3000 Ω.
Now, turn on the engine, and when it reaches operating temperature, measure again. It should read between 200 and 400 Ω.
If the sensor is good, turn the engine off, and with the ignition key in the "ON" position, check the voltage in the harness connector for the sensor. It should read approx. 5V.

Yes, a malfunctioning coolant sensor can definitely produce the symptoms you're having.

The fact that you got a code 9 means the computer is receiving some weird reading from the coolant temperature sensor circuit. As with any circuit, there's more than one thing that can be malfunctioning. However, 99% of the times it's either the sensor or the connector/wiring.

[beefmobile]

ok i changed the sensor and as soon as i bolted everything back up and cranked her up, the code was constant...at idle and all. so i drove to the gas station and the heat shot ALL the way up.....WTF???? is that a false reading or something?

[Inodoro Pereyra]

Did you test it before you replaced it?
How about the wiring?
Check that you have about 5V dc in the connector, like I explained above.

I',m fairly sure the high temperature reading was caused by a short circuit in the sensor wires. The good news is that it should be pretty easy to diagnose: just disconnect the sensor and turn the car on. The temp gauge should read "0". now, get somebody behind the wheel, and start fiddling with the sensor wires, moving them around a bit. If the gauge reading changes you have a short. Time to get a big supply of patience and start checking the wires, one by one...