P0121 2005 VW Passat TDI

I keep on getting code P0121 everytime I push the gas pedal. I have replace the throttle body, brake light switch and the gas pedal. None the fixes solve the problem. I have look at the ECU and the electric wire and they look fine. Can I get some help.

if you have access to VAG, look at the tps signal voltage as you increase throttle with the key on engine off. It should show 0-5v progressive. If it doesn't, you need to back probe the connections and look for continuity. probably simple but always difficult to pinpoint.

I don't have access to VAG at the moment is there any other way to troubleshoot without a VAG

You've thrown parts at it but not actually tested anything.

You'll need a decent volt meter and a wiring diagram. Make sure all the fuses are good, and that the ground points are good.

www.alldatadiy.com has the testing info.

But it is a pretty standard fare double variable resistor type pedal sensor. Six wires, three for each sensor. One ground, one 5v reference, the other the return signal to the ECU. So at least two of the pins should have ground, two should have approximately 5v with the key ON. That is easy enough to check.

I did that check with pedal senor:

Terminal 1 + Ground
Terminal 1 + 5
Terminal 2 + Ground
Terminal 2 + 3

I was reading less then a 1 volt on all of them with the key on. Does this mean I have a bad wire going to the ECU from the pedal senor.

I would check each wire from the pedal sensor connector to the ECU individually, yes.

Also poke around for critter 'leavings'.

So I recheck the wiring again for the voltage for the pedal senor. I'm not getting 4.5 volts or higher on Terminal 1 + 5. Where does pin 5 on terminal for the pedal senor go to

Does anyone know where pin 5 on the terminal from pedal senor goes to beside the ECU

So I found corrosion on the pins at the 15 pin block between the ECU and the pedal senor. I made a whole new wire hardness between the pedal to 15 pin block. I'm getting 4.5 volts or more on Pin 1 to ground, Pin 2 to Pin 3, Pin 2 to ground. But when I go between Pin 1 to Pin 5 on the voltages varies between +0.5 to -0.2. Is Pin 5 suppose to be ground? I check the continuity to pin 5 back to the ECU and its ok. The resistance is below 1.2 ohms. Also I have Vag Com cable. Can I please get some help.

I was able to get Vag-Com cable and got this code
Tuesday,29,June,2021,18:54:22:48890
VCDS Version: Release 21.3.0 (x64) Running on Windows 10 x64
www.Ross-Tech.com

Address 01: Engine Labels: 038-906-016-BHW.lbl
Control Module Part Number: 038 906 016 R HW: 028 101 198 2
Component and/or Version: R4 2,0L EDC G000AG 8900
Software Coding: 0150034
Work Shop Code: WSC 05311 000 00000
VCID: 2313EB4267CE17B3B21-5160
1 Fault Found:

16610 - Throttle Pedal Position Sensors (G79)/(G185)
P0226 - 000 - Implausible Signal - MIL ON
Freeze Frame:
RPM: 1449 /min
Torque: 78.0 Nm
Speed: 0.0 km/h
Load: 6.3 %
Voltage: 13.30 V
Bin. Bits: 00101000
Torque: 180.0 Nm
Bin. Bits: 0 11 0


Readiness: 1 1 0 1 0


How do decipher this to help me better.