If your CP Plus screen shows 412, 645 or 42, the window safety sensor is stopping the heater — and it's usually a 30-second fix. This is one of the heater's fault signals; for the gas/ignition faults see the CP Plus gas guide.
Why the heater stops. There's a window right beside your heater's exhaust vent (the small outlet on the outside wall of the van). A sensor cuts the heater off whenever that window is open, so exhaust fumes can't drift back inside. It's a safety cut-off — so the fix is simply to close that window properly.
The fix — close the right window
- Find the window nearest the heater — it's the one by the inside table, on the opposite side from the heater unit.
- Close it fully and latch it. Give it a firm push. A window that looks shut but hasn't quite latched is the most common cause — even a small gap trips the sensor.
- Clear the code on the panel: tap the rotary knob to acknowledge/delete the fault (the first tap may only wake the screen — tap again). If it doesn't clear, switch the panel off, wait 5 seconds, and switch it back on.
- The code should clear and the heater start up again.
Still showing 412 / 645 / 42 with the window definitely closed and latched?
That points to a faulty sensor — please get in touch and we'll take it from there. Please don't wedge or cover the sensor to get around it: it's what keeps exhaust fumes out of the van. Contact us and we'll sort it.
- 💬 WhatsApp — message us here
- 📞 Call us — available in your rental agreement