Problem with 2003 Jetti 1.8T transmission, drives only in 1st gear
00652 - Gear Monitoring: Implausible Signal Possible Causes : Automatic Transmission Fluid (ATF) Level not OK Vehicle Speed Sensor dirty/faulty, Impulse Wheel dirty or Installation faulty, Gearbox Speed Sensor dirty/faulty, Impulse Wheel dirty or Installation faulty, Multi-Function Switch faulty (but not detected), Clutch or Valve Body faulty, Automatic Transmission Fluid (ATF) Pump faulty. Possible Solutions: Check Automatic Transmission Fluid (ATF) Level, Check/Clean/Replace Vehicle Speed Sensor, Check/Clean/Replace Gearbox Speed Sensor, Check/Replace Multi-Function Switch, Check/Replace Clutch and/or Valve Body.
With that in mind, it might be as simple as a low fluid level, but unless you know what your doing, your best to have a mechanic diagnose it for you.
The shift solenoids go out frequently on these Jettas. A fluid flush may buy it some time but will need to eventually replace the valve body and/or the whole transmission if it goes too far. Valve body (and replace the filter while in there) is the cheaper choice if you do it before the whole transmission degrades too far.
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