1Z Error Codes: Troubleshooting & Explanation

Hello everyone,

Since yesterday, while driving over a bump in the road, my Passat TDI 66kW, engine code 1Z, manufactured in 1995, has been malfunctioning.

It occasionally starts to stutter and also doesn't respond to acceleration.

Furthermore, it sounds like the cylinders are communicating with the valves, and the timing belt seems to be in good condition.

While reading the error codes from the vehicle's memory using a Bosch KDS diagnostic tool, I retrieved the following error codes:


1. 045D Load signal generator terminal DF, implausible error, occurring sporadically.

2. 04D5 Electric idle speed control - intermittent fault.

3. 0226 Injection start control - intermittent fault.

4. 04DA - Intermittent short circuit to ground or positive terminal in the control unit.

After clearing the error memory, error codes 3 and 4 reappear intermittently, and sometimes even occur when the vehicle is idling.

Okay, my guess is that it's some kind of damaged cable or something, but where do I even start looking?

I hope a loose crankshaft pulley bolt is not the issue.

Or is it actually this damn control unit that's broken?

Thank you for all your help.

Burli.