Rational Combi Oven Error Code Service 42: Care Valve Y4 or Hose
Service 42 on a Rational SelfCookingCenter whitefficiency means solenoid Y4 Care is defective, the Care container hose is blocked or kinked, or the CDS sensor is not pulsing. Automatic cleaning stops, while cooking usually works. Make sure the container is full and its hose is straight, then call us if the message returns.
Medium: cooking continues, but automatic cleaning stops until the Care line is repaired.
- Code
- Service 42
- Maker
- Rational
- Equipment
- Combi ovens
- Applies to
- SelfCookingCenter whitefficiency (SCC_WE) family
What does Rational error code Service 42 mean?
Solenoid Y4 opens the line that carries cleaning liquid from the Care container into the oven. During an automatic clean the control opens Y4 and expects the CDS sensor to report pulses of flow. If the hose is kinked or blocked, the valve does not open, or no pulses are counted, the control cannot confirm that cleaner is arriving. It stops the program and displays Service 42. Cooking programs are not affected, and the message comes back whenever you start another cleaning cycle because the same check is repeated. The manual lists the hose from the Care container, the way Y4 operates, the CDS pulses, and crystallized cleaner in the small lines. That last point is worth noting: cleaner left standing can dry into crystals that narrow a line. The first job is to rule out an empty container or a pinched hose, then test the valve and the sensor.
Affected models and control systems
This relates to the Rational SelfCookingCenter whitefficiency (SCC_WE) family with automatic Care cleaning. Other Rational generations assign different message numbers.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- Service 42 appears after a cleaning cycle begins
- Cleaning stops and the cabinet is left partly dirty
- Care container looks full but no liquid seems to move
- Cooking programs run as usual
Possible causes
Listed in Rational's documentation
- Care container hose is kinked or blocked
- Solenoid Y4 does not open
- CDS sensor is not pulsing
- Cleaner has crystallized in the small lines
Other likely causes — what usually sits behind error code Service 42 on this control. A technician confirms which one it is before any part is replaced.
- A Care container swapped without reseating the pickup tube
- Cleaner left to dry in the line over a slow holiday week
Safe checks before calling for service
- Make sure the Care container is full and the hose leaving it is not kinked or pinched.
- Let the cabinet cool, then switch the oven off and on once.
- Start the cleaning cycle again only if the cabinet is cool.
- If Service 42 returns, call us and leave the panels closed.
- Until then, clean the cabinet by hand and rinse it well, and tell us what the display showed.
How a technician diagnoses error code Service 42
- Read the message history and confirm the container product and level.
- Trace the Care hose for kinks, blockage and crystallized cleaner.
- Test whether Y4 receives its signal and opens.
- Check the CDS pulse count during a short cleaning test.
- Flush or replace the line, or replace Y4, only after the pulse test shows where flow is lost.
- Y4 is wired to line voltage inside the housing, so testing it means live work behind panels.
- Cleaning concentrate in the lines can irritate skin and eyes when a line is opened.
How error code Service 42 differs from similar codes
Service 41 involves the moistening valve Y3 and the oven's water, while Service 42 involves Care valve Y4 and the container line for cleaner.
Technical reference
- Document
- RATIONAL SelfCookingCenter Original operating instructions
- Models / control
- SelfCookingCenter whitefficiency (SCC_WE) family
- Section
- Fault messages table, printed pp. 188-191 (PDF pp. 188-191 of 201; footer reads n / 198)
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Rational combi oven error codes
What is the Care container?
It holds the cleaning liquid used by the automatic cleaning program. A blocked hose from it stops the cycle with this message.
How do I tell Service 42 from Service 41?
Service 41 concerns moisture valve Y3, while Service 42 concerns Care valve Y4. Both stop a cleaning cycle, so the number is the clue to give us.
Can I clean the oven another way?
Yes, by hand with the maker's named cleaners once the cabinet is cool, rinsing well.
Need help with Rational error code Service 42?
A technician confirms the cause on site and gives you the price in writing before any work starts.