There are 3 different possible faults:
P1112: Port Deactivation Solenoid Valve Actuation Error
Mechanical Function Check
•Verify mechanical system functions/components
•The Twinport solenoid valve is stuck or moves too slow.
•Check/clean solenoid valves
•Solenoid valve-vacuum tank
•Distributor housing to solenoid valve-vacuum tank
•Vacuum hose

P1112: Port Deactivation Position Sensor Circuit Low Voltage
•Short to ground in circuit to control unit terminal 44 (X54)

P1112: Port Deactivation Position Sensor Circuit High Voltage
•Short to voltage or interruption in circuit to control unit terminal 44 (X54)

 

hi thanks for the reply ive checked everything I can think of ive changed the complete solenoid and still got the same issue ive checked the vacuum hose and seems okay cant think what else to check

 

P1112: Port Deactivation Position Sensor Circuit High Voltage
•Short to voltage or interruption in circuit to control unit terminal 44 (X54)

this is the fault I have do you know if there is any common fixes for this

 

Have you disconnected the battery, leave for 30 mins, the reconnect..mind you may need the radio code if it's the standard vauxhall one in the car..

 

Ive tried disconnecting the battery over night and still same issue. my friend is a fully qualified mechanic and he seems to think a new ecu is needed

whats the possibility of this been the issue iv also read somewhere that it could be the inlet manifold any more advise will be great thanks

 

I would try everything else before you go down the ECU route, i wise man once said test the components, dont be a parts fitter....wasn't me from Fred in Essex.

 

http://www.corsa-c.co.uk/forum/showthread.php?342431-is-a-new-ecu-the-only-way-to-fix-p1112

have ya seen this post.

 

all the info I can find all relates to voltage too low and not voltage too high yesterday I changed the wiring loom just in case I caught any of the wires when I was putting the engine in the engine was running fine when it was in the original vehicle

 

Hi. Just thought I would add a reply even though it was a good few months back.
I had a similar issue but on an astra.
Port deactivation sensor High voltage.
So it turns out, it was the sensor that was at fault and not the solenoid.
Reading the live data from the car, when the twinport actuation rod was moved, nothing changed to the voltage output of the sensor.
It was reading a constant 3 volts.
Vauxhall will not supply this sensor, they only want to sell you the complete manifold at a vast cost of £415 plus vat.
After a lot of trolling t'internet I managed to find out that an Astra/corsa throttle position sensor is identical at a cost of £28 plus vat.
Item fitted and now working fine.
Makes a heck of a difference to the performance of the car too.

 

Yes i think when sensor voltage is too high it might mean its not being grounded out like it should be, from Fred in Essex.