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2000 Vauxhall Zafira 1.8 Petrol P0443 Code: Evap Valve Not Closing Properly

Model: 2000 1.8 petrol Vauxhall Zafira Fault Code: P0443 Posted: 2014-03-06 05:06

Hi everyone, I'm troubleshooting a persistent P0443 diagnostic trouble code on my 2000 Vauxhall Zafira 1.8 petrol model. The evaporative emission control system is showing an issue with the purge valve. I've confirmed that power is reaching the valve when the ignition is on. When I manually earth the valve (using the brown wire), it clicks as expected — indicating basic operation. However, when the valve is closed, there's still a slight suction in the pipe, which I'm concerned about. Should the valve be fully sealed when closed? If so, why does it still suck slightly? I've also tested for 'wooshing' noise when removing the fuel filler cap — no such sound occurs, suggesting the system isn't leaking at the tank level. Despite clearing all DTCs and replacing the purge valve/solenoid unit, the P0443 code continues to reappear. I can confirm 12V on the black wire (power) and a click when earthed via the brown wire. The issue persists even after checking connections and pipe integrity. My question: Is it normal for one of the valve wires to show voltage when earthed? If not, could this indicate an internal short or diaphragm failure within the solenoid? Any insights or testing methods would be greatly appreciated.

Related fault codes
P0443
Comments (6)
Anonymous 2014-03-06 07:06

The valve should be fully closed and show no suction when sealed. Any residual suction suggests a problem with the diaphragm or internal sealing.

Anonymous 2014-03-06 10:01

Thanks for confirming — I was unsure whether the second wire (earthed) should have voltage. It's showing power when earthed, which is unusual. Normally only one wire carries 12V from the ignition; the other connects to the PCM. This could indicate a wiring fault or internal short in the solenoid.

Anonymous 2014-03-07 07:49

This behavior strongly suggests an internal short within the purge valve solenoid, possibly due to a damaged diaphragm or faulty coil.

Anonymous 2014-03-12 11:21

Update: I've replaced the purge valve/solenoid and verified all connections and pipework. Still getting P0443 after clearing DTCs. Power is present on the black wire (12V), and the valve clicks when earthed via the brown wire. The code returns immediately — likely indicating a circuit malfunction. What should I do next? Any suggestions?

Anonymous 2014-03-12 11:37

To diagnose further: unplug the solenoid. One wire should have constant 12V (power), and the other must connect directly to the PCM with full continuity. Use a scan tool to command the valve — this will help determine if it's responding correctly. Note: This is not a domestic or imported model in my region, so I don't have access to official wiring diagrams.

Anonymous 2014-03-12 12:48

Thanks for the tip! I'll now trace the second wire back to the PCM plug and test continuity from the PCM terminal to the valve end. If there's no continuity or unexpected voltage, that would point to a faulty connection or internal solenoid failure.