Mechanics

VOLKSWAGEN JETTA SENSOR PROBLEM

2001 Volkswagen Jetta • 140 miles

Hey guys I'm looking for some help with an idle issue. The engine light is on and if I remember correctly the code that is coming up is P1296. Last summer I replaced the temp sensor and about 2months ago I replaced the breather hose bc it had worn out and broke. I assumed that the idle/bucking issue was do to the broken hose. Its the worse in first gear and usually works (or at least I cant notice it) once I get moving in 2nd. However, the issue is getting worse and I certainly dont want to keep driving my car this way. What I do know or have noticed is that when its warmer outside it seems to work better. Also, the car never runs at the temperature that it use to, if anything the needle is barely about the first couple lines. It use to be pegged straight up(190?). Can a brand new temp sensor be bad? What do I do? Thanks for any help.
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X_jetta_x
March 27, 2013.




To properly repair your fault which is "cooling system malfunction" you need to replace your thermostat. You will need to replace the seal and plastic adapter/housing as well. These parts are pretty cheap.

When you replaced the sensor, the old one probably had a black top. The sensor you put in SHOULD of been green. If it wasn't, you need to go to a VW dealer and purchase a new ECT with a green-top, the sensors have been superseeded.

Now when you say you have idling issues, what exactly happens? Because in your description you said it happens in 2nd gear, which is impossible because idling is when the car is stopped and the engine is still running. Once you touch the accelerator pedal or the wheels are moving, you are no longer idling.

Replace the thermostat and install a green top ECT and the fault will be fixed.

F4I_guy
Mar 27, 2013.
I dont recall if it was a green top or not but I will look. If it isnt green would be that be the potential solution? From what I understand if the computer does know the cars temperature then the car wont idle/run properly. Is that accurate?

The idle problem- When I turn the car on the rpms pop and then eventually (10-20seconds usually)drop to what its suppose to idle at(7800?), But it flutters. If I hit the gas, while parked, itll pop up and sometimes start idling properly. However, when I drive it often struggles at starts/stops and even sometimes stalls out when I stop. When I try to move off a stop I more than often have to give it more gas to rev the motor up as I engage the clutch or it bucks. Rarely anymore will it drive normal. When it has its been around 55-60 outside(which is about 20degrees warmer than the normal around here currently). I dont know if any of what I said makes any sense but I can sent a video of what im trying to describe if that helps. Thank you for your help!

-Joe

Tiny
X_jetta_x
Mar 28, 2013.
I'm also only getting about 300mpg when I use to get 380-400. Which obviously makes sense.

Tiny
X_jetta_x
Mar 28, 2013.
Your idle issue might be a dirty/clogged throttle body. I would remove the throttle body from your car (cause it's fairly easy) and give it a good clean with throttle cleaner or carbon cleaner and a toothbrush. If you vehicle is electronic throttle (so no throttle cable) you will have to re-adapt the throttle, which you need a scantool for.

A faulty ECT can cause the issue you described.
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F4I_guy
Mar 28, 2013.

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