P1426 help needed

[Brah]

I've searched and exhausted all my options.

My 96' 2.0 is throwing code P1426.

I've replaced my gas cap, ive replaced the evap purge valve, and checked the wiring to the valve.

I'm at a loss here? Does anyone have any suggestions?

[Seamus68]

quick question,

After you replaced those parts...did you clear the codes with a scanner?

[Anony00GT]

Assuming you did clear the codes, and this code came right back...

Is this the ONLY code you've got?

Did you install a new N80 purge solenoid, or at least a verified good one? Or just a used junkyard unit? Check resistance across the two pins on the solenoid, what are the results?

How did you check the wires to the purge solenoid? Did you reference the wiring diagram and check the WHOLE circuit with a DVOM, both sides? This code indicates an electrical malfunction in the N80 circuit, the gas cap has no effect. In fact, the ECU doesn't even test the purge solenoid and LDP/tank side in the same test, it combines two tests to set one emission monitor.

[DrP]

P1426 "Tank Ventilation Valve Open Circuit".

Did you check the tubing for vacum leaks?

[Anony00GT]

P1426 "Tank Ventilation Valve Open Circuit".

Did you check the tubing for vacum leaks?

No. A problem in the N80 side of the vapor system would throw P0441. This is an electrical circuit code, and a perfect example of why generic OBDII isn't always the best way to diagnose a VW.

http://wiki.ross-tech.com/wiki/index...4/P1426/005158

[Brah]

Assuming you did clear the codes, and this code came right back...

Is this the ONLY code you've got?

Did you install a new N80 purge solenoid, or at least a verified good one? Or just a used junkyard unit? Check resistance across the two pins on the solenoid, what are the results?

How did you check the wires to the purge solenoid? Did you reference the wiring diagram and check the WHOLE circuit with a DVOM, both sides? This code indicates an electrical malfunction in the N80 circuit, the gas cap has no effect. In fact, the ECU doesn't even test the purge solenoid and LDP/tank side in the same test, it combines two tests to set one emission monitor.

Yes I cleared the codes and yes this is the only code I have.

I installed a junkyard unit, but I tested both and both gave me good resistance.

The N80 is supposed to read 22-30ohms. The original unit read 25ohms, the new unit read 28.5ohms.

As per the wiring, I checked both pins of the connector for voltage. That's it tho.

[Anony00GT]

IIRC one pin should have battery voltage with the key on, supplied through the fuel pump relay. The other is a PWM ground controlled by the ECU.

Check for battery power. If one pin has it, use a DVOM to check resistance across the other wire all the way from the N80 to the ECU.

[Brah]

IIRC one pin should have battery voltage with the key on, supplied through the fuel pump relay. The other is a PWM ground controlled by the ECU.

Check for battery power. If one pin has it, use a DVOM to check resistance across the other wire all the way from the N80 to the ECU.

iirc, I had about 6v on one pin, again iirc. I'll verify both.