F16 on a Dimplex heat pump: Excessive current draw detected (overcurrent protection)
Short answer
On a Dimplex heat pump, F16 means: Excessive current draw detected (overcurrent protection). The heat pump stops until the fault clears or is reset. An engineer is needed to fix the cause. The wording differs by model range — each is shown below.
Reviewed 23 September 2026 · 2 sources
What it means
On the LA MI inverter outdoor air-to-water (LA 6/9/12/16 MI)
The manual says: Excessive current draw detected (overcurrent protection).
Part involved: Current transformer on refrigerant PCB.
When it shows: Outdoor current above 27.9 A detected by CT; 3 times in 20 minutes.
Likely causes:
- Excessive refrigerant.
- Faulty main refrigerant PCB.
On the WPM heat pump manager platform (error-code grouping)
The manual says: Brine pressure monitoring: the brine pressure monitor in the brine circuit has tripped.
Part involved: Brine low-pressure controller (accessory).
When it shows: Fall in brine pressure detected by optional low-pressure brine controller.
Likely causes:
- Brine pressure too low (loss of brine/antifreeze, leak).
Is it safe?
On the LA MI inverter outdoor air-to-water (LA 6/9/12/16 MI)
Switch the heat pump off at its isolator and call an engineer.
| Does the heat pump stop? | Yes |
|---|---|
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: unknown.
Manual reset: Clear via control panel per Dimplex article (method shown as image).
On the WPM heat pump manager platform (error-code grouping)
| Does the heat pump stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The heat pump stops until the fault clears or is reset.
Resetting itself: After rectifying the fault the heat pump can be restarted; switching off the control voltage also acknowledges the fault (WPM Touch p.54). On text-display WPMs press Esc to acknowledge (EconPlus EN-16).
Manual reset: Acknowledge after rectification.
What you can check
On the LA MI inverter outdoor air-to-water (LA 6/9/12/16 MI)
- Note the code and contact the installer or Dimplex service.
On the WPM heat pump manager platform (error-code grouping)
- Note the fault code, the heat pump model (type plate) and controller software version shown in operating data, and contact the installer/Dimplex service.
What the engineer will check
On the LA MI inverter outdoor air-to-water (LA 6/9/12/16 MI)
- Isolate the heat pump from mains before any work.
- Check refrigerant charge (F-Gas).
- Check refrigerant PCB.
Who to ask for: refrigeration / heat pump service engineer.
Certification: F-Gas (refrigerant handling) certification for any refrigerant-circuit work.
On the WPM heat pump manager platform (error-code grouping)
- Check the brine pressure.
- Leak-check ground loop and indoor brine pipework.
- Re-pressurise with correct antifreeze mix.
Who to ask for: ground source / heating engineer.
What you might notice
Sources
- GDHV Help Centre article: i have f16 error on my la mi heat pump what does this mean ↗ · GDHV article (modified 2023-02) · page n/a (web article) · Reviewed 23 September 2026
- Dimplex WPM Touch heat pump manager - Operating instructions for users and specialists (Order no. 452117.66.02-EN, WPM3.13 / Display 1.15) ↗ · 452117.66.02-EN FD 0302 · page 54 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026