Question 1

Flush function works, but water in bowl empties slowly or not at all

Accepted Answer

Possible cause: Discharge piping is pinched, kinked, too high (exceeding 4 ft / 1.2 m upward vertical limit), or blocked. Check discharge piping, reroute if necessary, or close seacocks and clear blockage

Question 2

Macerator pump makes unusually loud noise or continually trips breaker

Accepted Answer

Possible cause: Foreign material present in pump chamber. Close seacocks and clear foreign material from pump chamber

Question 3

Flush cycle is not activated after pushing on flush switch

Accepted Answer

Possible cause: Holding tank is full shutting down power via relay, electrical power is disrupted, or switch is malfunctioning. Empty holding tank, check wiring and circuit breakers or fuses, or replace flush switch

Question 4

Insufficient or no water enters the bowl

Accepted Answer

Possible cause: Water supply line is pinched/kinked, water valve screen is blocked, intake water filters are blocked, or water valve is malfunctioning. Check water supply line, clear blockage at water valve or intake water filters, or replace water valve

Question 5

Insufficient or no water enters the bowl.

Accepted Answer

Possible cause: Water supply line is pinched/kinked, water valve screen is blocked, intake water filters are blocked (raw water system), water valve is malfunctioning, or raw water impeller is malfunctioning.. Check the water supply line, clear blockages at the water valve or intake water filters, replace the water valve, or replace the raw water impeller.

Question 6

The flush function works, but the water in the bowl empties slowly or not at all.

Accepted Answer

Possible cause: The discharge piping is pinched, kinked, too high (exceeding 4 ft / 1.2 m total upward vertical loop), or blocked.. Check the discharge piping, reroute to ensure vertical loops do not exceed 4 ft (1.2 m), or close seacocks and clear any blockage.

Question 7

The macerator pump makes unusually loud noises or continually trips the circuit breaker.

Accepted Answer

Possible cause: There is foreign material in the pump chamber.. Close the seacocks and clear any foreign material from the pump chamber.

Question 8

The flush cycle is not activated after pushing the Flush switch.

Accepted Answer

Possible cause: Holding tank is full shutting down power via relay, electrical power is cut/disrupted, Flush switch is malfunctioning, or electric motor is malfunctioning.. Empty the holding tank, check wiring and circuit breakers/fuses, replace the Flush switch, or replace the electric motor.

Error Code / Indicator	Symptom / Meaning	Step-by-Step DIY Fix	Suggested Actions
`N/A`	Flush function works, but water in bowl empties slowly or not at all Possible Cause: Discharge piping is pinched, kinked, too high (exceeding 4 ft / 1.2 m upward vertical limit), or blocked	Check discharge piping, reroute if necessary, or close seacocks and clear blockage	DIY Safe
`N/A`	Macerator pump makes unusually loud noise or continually trips breaker Possible Cause: Foreign material present in pump chamber	Close seacocks and clear foreign material from pump chamber	DIY Safe
`N/A`	Flush cycle is not activated after pushing on flush switch Possible Cause: Holding tank is full shutting down power via relay, electrical power is disrupted, or switch is malfunctioning	Empty holding tank, check wiring and circuit breakers or fuses, or replace flush switch	DIY Safe
`N/A`	Insufficient or no water enters the bowl Possible Cause: Water supply line is pinched/kinked, water valve screen is blocked, intake water filters are blocked, or water valve is malfunctioning	Check water supply line, clear blockage at water valve or intake water filters, or replace water valve	DIY Safe
`N/A`	Insufficient or no water enters the bowl. Possible Cause: Water supply line is pinched/kinked, water valve screen is blocked, intake water filters are blocked (raw water system), water valve is malfunctioning, or raw water impeller is malfunctioning.	Check the water supply line, clear blockages at the water valve or intake water filters, replace the water valve, or replace the raw water impeller.	DIY Safe
`N/A`	The flush function works, but the water in the bowl empties slowly or not at all. Possible Cause: The discharge piping is pinched, kinked, too high (exceeding 4 ft / 1.2 m total upward vertical loop), or blocked.	Check the discharge piping, reroute to ensure vertical loops do not exceed 4 ft (1.2 m), or close seacocks and clear any blockage.	DIY Safe
`N/A`	The macerator pump makes unusually loud noises or continually trips the circuit breaker. Possible Cause: There is foreign material in the pump chamber.	Close the seacocks and clear any foreign material from the pump chamber.	DIY Safe
`N/A`	The flush cycle is not activated after pushing the Flush switch. Possible Cause: Holding tank is full shutting down power via relay, electrical power is cut/disrupted, Flush switch is malfunctioning, or electric motor is malfunctioning.	Empty the holding tank, check wiring and circuit breakers/fuses, replace the Flush switch, or replace the electric motor.	DIY Safe

Dometic MasterFlush

Technical Specifications

Master Troubleshooting & Diagnostics Matrix