Join Date: Jun 2006
Location: Eastern ON Canada
Car: 07 OBW 2.5i D-4AT
Feedback Score: 5 reviews
Welcome to the forum.
A quick suggestion: Include the year and model of your car (& engine, transmission) with the post or in the permanent info in the left column. Helps focus . . .
As indicated in the linked thread, the P0028 is a code related to the variable valve lift system, namely:
DTC P0028 INTAKE VALVE CONTROL SOLENOID CIRCUIT
RANGE/PERFORMANCE (BANK 2)
P0028 is one of the diagnostic trouble codes that will turn the CEL on as soon as it is detected. If the problem goes away on its own, it will clear the CEL after three consecutive driving cycles without the fault showing up. The code itself will be stored in the ECM memory for 40 consecutive driving cycles without a recurring fault. (In both cases, provided the codes are not cleared from memory.)
The troubleshooting procedure involves first checking the wiring to the solenoid to make sure it isn't open or shorted. (This seems to be a possibility in the Forester link) Then the code is cleared and the car started at idle (only). If the code returns, the solenoid has to be replaced. (Perhaps the dealer already did the initial testing and eliminated the wiring as a cause).
There are two solenoids, one on each side of the engine. I'm not sure which is Bank 1 and which is Bank 2. The one on the RHS (passenger) is at the back of the head, and the one on the LHS is at the front of the head. The solenoid valves themselves are quite accessible; however, for some reason, the service manual requires the solenoid valve holder to be removed as well, and on the LHS this entails removing the timing belt, left cam sprocket and rear timing belt cover. (Perhaps the solenoids and the valve holders have to be replaced together, otherwise it seems to me the solenoid valve itself could be replaced with far less work.)
Depending on your year and mileage, this might be covered under the drive train warranty.
You could have the code cleared and see if the CEL comes on again, although I suspect that if the dealer was concerned, it might have done this as well.