Your Truma system heats the van's air and your hot water. This guide is for the CP Classic panel — the one you operate with a turn knob, where faults show as red or yellow blinks you count — on a diesel heater.
Wrong panel or fuel?
- Runs on a gas bottle, or this doesn't match your faults → Truma CP Classic (Gas) troubleshooting
- Panel shows numbers on a screen instead of a knob → that's the CP Plus, not this guide.
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1. Outer control knob for heating mode 2. Inner control knob for temperature (1 – 5) 3. Yellow LED lit, “Boiler heat-up phase” Yellow LED flashing “Warning” Red LED lit, red LED flashing “Fault” 4. Green LED lit, “On” 5. Hot water mode - temperature 60 °C 6. Hot water mode - temperature 40 °C 7. Rotary switch “Off” 8. Air heating mode 9. Air heating and hot water mode |
Good to know before you start
- Your heater runs off the van's diesel tank — there's no gas bottle to check.
- Air heating takes up to ~80 minutes to reach full temperature; hot water around 20. Give it time before deciding it's faulty.
- On the panel: green = on, yellow = warming up or a warning, red = fault.
Try these first — they fix most cases
1. Turn the temperature up.
Green light on but no heat almost always means the dial is set below the current room temperature. Turn it toward 5 and wait a few minutes.
2. Close every window — firmly.
A single window even slightly open (including the small one by the table) trips a safety sensor that shuts the heater off. Walk around and give each one a firm push. (Panel showing yellow ×3? This is it.)
3. Charge the leisure battery.
No lights at all, or a yellow warning blink, is most often a low battery — this is the single most common cause. Plug into shore power at the driver-side socket, or run the engine for about 30 minutes, then switch the heater on again. → Charging your leisure battery
4. Check your diesel and park level.
The heater draws from your fuel tank and shuts itself off before the tank runs dry, so you always keep enough to drive — which means it can stop with fuel still showing. Top up, park on level ground (a slope alone can stop it), then switch on. It runs two automatic start attempts to re-prime the fuel line, so give it a few minutes; if it doesn't catch, switch off and on once to retry.
What the fault lights mean
- Green flashing after you switch off — normal. It's a short cool-down run and stops on its own within about 5 minutes.
- Yellow ×1 or ×2 — battery voltage low (or, rarely, too high). Do step 3.
- Yellow ×3 — a window is open or ajar. Do step 2. → Closing the window sensor
- Yellow ×4 — airflow is blocked, or (if you're only running hot water) the boiler is empty. Check nothing is covering the warm-air outlets or the intake grille, and top up the fresh-water tank. → Clearing airway obstructions
- Yellow ×6 — water too hot in summer/water mode. Top up the fresh-water tank so the boiler has water.
- Yellow ×5, ×7, ×8, or a steady/other red light — an internal fault we need to handle. Please don't try to open or repair anything. Contact us (below) and we'll arrange the fix
Still no heat?
Contact IndieCampers roadside support and we'll get you sorted.
For the complete manufacturer instructions, the Truma CP Classic operating manual (PDF) is attached in the box below.