Question 1

The toilet flushes, but the bowl drains slowly or doesn't drain

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

The macerator pump is unusually noisy, or keeps tripping the breaker

Accepted Answer

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

Question 3

Pressing the flush switch doesn't start the flush cycle

Accepted Answer

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

Question 4

Little or no water is entering 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

Little or no water is entering 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 toilet flushes, but the bowl drains slowly or doesn't drain.

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

Pressing the flush switch doesn't start the flush cycle.

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.

Dometic MasterFlush

Technical Specifications

Master Troubleshooting & Diagnostics Matrix

Error Code / Indicator	Symptom / Meaning	Possible Cause	Step-by-Step DIY Fix	Suggested Actions
`N/A`	The toilet flushes, but the bowl drains slowly or doesn't drain	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`	The macerator pump is unusually noisy, or keeps tripping the breaker	Foreign material present in pump chamber	Close the seacocks and clear anything foreign from the pump chamber	DIY Safe
`N/A`	Pressing the flush switch doesn't start the flush cycle	Holding tank is full shutting down power via relay, electrical power is disrupted, or switch is malfunctioning	Empty the holding tank, check the wiring and circuit breakers/fuses, or replace the flush switch.	DIY Safe
`N/A`	Little or no water is entering the bowl	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`	Little or no water is entering the bowl.	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 toilet flushes, but the bowl drains slowly or doesn't drain.	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.	There is foreign material in the pump chamber.	Close the seacocks and clear any foreign material from the pump chamber.	DIY Safe
`N/A`	Pressing the flush switch doesn't start the flush cycle.	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