G4204A quat pump Error messages –Drive off and –Outlet valve block position

HI, I have a G4204A quat pump which displays the error “Drive off” and “Outlet valve block position” in LabAdvisor. Please can anyone tell me what this means and how I might be able to fix it. We don’t have much money (academia!) and would like to fix it without calling out an engineer if possible. Thanks

  • Hello BlueMoon,

    Either the pump drive is defective or you have a totally clogged outlet ball valve which is causing excessive current when the pump tries to initialize on power on.  

    Suggest turning the pump off, carefully remove the outlet ball valve [refer to the User Manual], then power on the pump and see if it shows the same error.  If yes, then you will need to call Agilent to get the pump drive replaced.  If no error, then you can try sonicating the outlet ball valve in a beaker with water [assumption is you are running in reverse phase], assemble it and see if the error is shown.  If yes, then you will need to purchase and replace the valve.

  • Thanks abasdeo,

    This is really helpful. I had suspected as much but couldn't find anything definitive in the manuals. I have been working on the outlet valve and the rest of the flow path and i am pretty certain there are now no blockages there. I took out the valve and turned on the pump and software and still get the Error, so I guess it is a call to Agilent next.



  • Hey, this is not the case. When the pump is not initialized (not ready) the information Drive off and out valve block position are present. The out valve block position refers to the position of the multipurpose valve. The multipurpose valve is in the blocked position.This has nothing to do with an outlet ball valve being blocked or a defective pump drive.


  • Hey Bluemoon, you have just told us the status of the instrument and not the error. Could you provide more information? Is the module red, what happens when hovering over the red? What error code is shown there? As I mentioned in the comment above, the pump shows the information as you have when it is not yet turned on by the software. Could it be that you just have not yet turned the pump on?

  • Hi kbusch. Thanks for this. I am completely new to using this hplc and have just been set the task of getting it going! I hadn't realised that the pump drive was turned off so i have now turned that on and the message has gone.

    The machine was not left in a very good state and I am tracing through the flow path. Currently got a big leak from the outlet valve to the heat exchanger so the next step is to get a new gold seal as the current one looks a bit bent. I am worried that it will need a new heat exchanger though as that is quite twisted. I can get liquid through it but not sure if it will ever seat properly on to the seal. I think this is turning into my life's work and I am learning a lot!!

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