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BOSCH Dishwasher Troubleshooting

Dishwashers produced by the German engineering and electronics brand Bosch are rather reliable and efficient. In case of a dishwasher issue most basic models require the same approach. Identify the problem, then check the possible cause and try to tackle it using the information from the chart below.

 

PROBLEM POSSIBLE CAUSE SUGGESTED ACTION
Washability problems (dishwasherwon't clean properly) › Inappropriate dishwasher detergent used
› Blocked or clogged upper/ lowerspray arms
› Water doesn't circulate properlydue to debris in circulation motorimpeller
› Instruct customer to use a powdered dishwasher detergent (e.g. Cascade powder)
› Check spray arms – clean or replace as needed.

› Twist and remove filter, then remove debris from right side of sump where water enters circulation pump impeller. If debris has jammed impeller, turn off and pull out dishwasher, remove tank, remove circulation motor and unscrew and clean out imp
HINT: If impeller is damaged, replace entire impeller assemb ly or it won't seal adequately.
  › Filter not locked down securely, allowing debris to enter sump.
CAUTION: Use caution when removing debris from sump to avoid being cut by sharp debris such as aluminum can tabs or broken glass
› Twist and remove filter, then remove debris from sump. Instruct customer to twist and lock filter (cylinder) securely into sump.
HINT: Due to high temperature rinse (161 o breaking down food debris and triple filtering system trapping food debris, filters shouldn't normally clog up. Problem often caused by filter not being securely locked down. Instruct customer to twist and l
HINT: Water level will not affect washability as water fill is measured by pressure, not time – water level cannot be adjusted › Drain hose behind dishwasher doesn't have an adequate loop. 
› Partially clogged air gap, allowing wastewater from prior washes to circulate in dishwasher.
› Loop drain hose behind the dishwasher (with the top of the loop) at least 20" above the floor.
› Unclog sink air gap.
  › Water doesn't drain properly NOTE: Cleaning sink air gaps is not covered under warranty.
  › Soap doesn't enter dishwasher due to dispenser actuator (A2) failure.
HINT: Must pull out dishwasher and remove left side panel to access float switch.
› Turn off dishwasher and test actuator –
replace if faulty.

HINT: One "wax" motor operates both the detergent and rinse aid dispensers through a mechanical linkage. The system always resets when door closes. Check linkage by moving it manually. Check "wax" motor by running a continuity check on its terminals.
› Suds or foam remains in dishwasher. › Too much detergent used.
› Improper detergent used (other than powdered dishwasher detergent)
› Dishwasher doesn't drainproperly.
› Instruct customer to use less.
› Instruct customer to use a powdered dishwasher detergent (e.g. Cascade powder).
› Dishes won't dry properly. › Rinse aid not used. › Instruct customer on using rinse aid – dishes won't dry without it.
› Dishwasher has an odor. › Standing water in dishwasher
sump.
› Unclog air gap. Make sure top of drain hose loop (behind dishwasher) is at least 20" above floor (add a loop in hose if there isn't one).
  HINT: Water level in sump should be at or below drain motor cover.
› Standing water in dishwasher base.

› Minerals in customer water supply

› Food debris in dishwasher filters
› Turn off dishwasher, drain water manually from dishwasher base and correct source of water leakage.

› Recommend customer to get water tested and use an appropriate water softener.

› Clean dishwasher filters.
› Dishwasher won't run or indicator lights won't come on. › Dishwasher not turned on
› No power to dishwasher
› Door ajar or on/off switch failed

› Door latch has broken

› Indicator light failed
› Turn on/off switch on.
› Check customer circuit breaker, fuse box or power connections.
› Turn off dishwasher and check door or on/off switch - adjust or replace them.
› Turn off dishwasher and replace door latch – instruct customer to not pull on door without pulling latch
› Run test program to see if light failed. If so, turn off dishwasher and replace indicator light
Water doesn't drain properly › Kink in drain hosec
› Dishwasher filter(s) or sump clogged
› Drain motor impeller clogged
› Straighten or replace drain hose
› Clean dishwasher filters or sump

› Turn off dishwasher, remove drain motor cover (in sump) and clean impeller. If necessary, remove drain motor to clean impeller.
CAUTION: Use caution when removing debris from sump to avoid being cut by sharp debris such as aluminum can tabs or broken glass. › Kitchen sink or sink air gap clogged


› Drain motor (m3) failed

› Timer (SHU 30/40 models ) or module (all other models ) failed.

› Improper drain connection height (< 20" or 508mm above floor).
› Unclog sink or sink air gap 

NOTE: Cleaning sink air gaps or sinks are not covered under warranty.
› Turn off dishwasher and measure resistance at motor terminals (≈ 16.5 ? ) Replace faulty motor
› Check voltage at and wiring to timer or module. Turn off dishwasher and replace faulty timer or module (for SHU/I 43/53 models, install existing module jumper onto new module).
› Install drain height and sink air gap acording to local codes
Dishwasher won't stop filling or won't stop draining. › Water in dishwasher base from leaky or loose hose.
› Dishwasher isn't level, causing float switch (e6) to operate.
› Float switch or diaphragm (e6) failed.
› Debris in dishwasher base activated float switch (e6 ).
› Turn off dishwasher, drain water manually from dishwasher base and reinstall or replace hose
› Level dishwasher using front and rear leveling legs 
› Turn off dishwasher and replace float switch or diaphragm.
› Turn off dishwasher and remove debris from dishwasher base
Water fills too slowly › Low customer water supply pressure
› Inadequate customer water supply piping.
› Scale in customer supply piping or dishwasher piping/parts from hard water.
› Adjust customer water supply pressure (to 5-20 psi or 0.3-8.27 bars).
› Install appropriate piping to dishwasher according to local codes.

› Clean or replace clogged piping/parts and have customer get water tested and use appropriate water softener
Water won't fill

NOTE: An "F" fault code in the display shows there's a filling problem ( not filling, over-filling, underfilling or water in the base ). The fault code can't be reset manually – it will reset itself 15 minutes after the dishwasher has been turned on (aft
› Customer water supply turned off or disconnected
› Water valve (s2 ) failed.



› Water level switch (f1 ) failed.
› Timer (SHU 30/40 models ) or module (all other models ) failed

› Water in dishwasher base operated float switch (e6)
› Reconnect and turn on customer water supply

› Check resistance @ water valve terminals (≈ 1000 ?). Turn off dishwasher and replace faulty valve.


› Turn off dishwasher and replace faulty level switch
› Check voltage at and wiring to timer or module. Turn off dishwasher and replace faulty timer or module (for SHU/I 43/53 models, install existing module jumper onto new module).
› Turn off dishwasher, drain water manually from dishwasher base, find source of leaking water and fix water leak.
Detergent or rinse aid won't dispense properly › Dispenser actuator (A2) failed
› Detergent dispenser door is jammed
› Turn off dishwasher and replace actuator
› Free jammed detergent dispenser door
Refill rinse aid light won't come on › Rinse aid level switch failed (reed switch e3 on standard dispensers or built-in actuator on top-load dispensers). › Turn off dishwasher and replace reed switch (standard dispensers) or top-load dispenser
Water doesn't circulate › Circulation motor (m2 ) failed
› Timer (SHU 30/40 models ) or ?module (all other models ) failed
› Turn off dishwasher and replace motor
› Check voltage at and wiring to timer or module. Turn off dishwasher and replace faulty timer or module (for SHU/I 43/53 models, install existing module jumper onto new module)
Water doesn’t heat up properly › Hi-Limit (f5) tripped and failed to reset.


› NTC (temperature sensor) failed.

› Heater (r1) failed



› Water flow switch (e5 ) failed



› Timer (SHU 30/40 models ) or module (all other models ) failed
› Run test program & measure current to dishwasher. If current ≈ 11A, Hi-Limit is OK. If not (and for all other models), turn off dishwasher and measure resistance @ Hi-Limit terminals (≈ .3 ?). Replace faulty Hi-Limit.
› Turn off dishwasher and check resistance of NTC (≈ 55 k? @ 72o F). Replace faulty NTC
› Run test program & measure current to dishwasher. If current ≈ 11A, heater is OK. If not (and for all other models), turn off dishwasher and measure heater resistance (≈ 11 ?). Replace faulty heater
› Run test program & measure current to dishwasher. If current ≈ 11A, flow switch is OK. If not, remove flow switch microswitch, close its contacts & measure its resistance (≈.4 ?). Replace faulty flow switch.
› Check voltage at and wiring to timer or module. Turn off dishwasher and replace faulty timer or module (for SHU/I 43/53 models, install existing module jumper onto new module)
Dishwasher cycle runs too long, yet dishwasher washes, rinses and shuts off OK › Customer hot water supply isn't hot enough (< 140o F/ 60 oC). › Adjust hot water supply according to local codes.
Water leaks from front of dishwasher › Blocked or clogged upper or lower spray arms
› Excessive foaming
› Check spray arms – clean or replace as needed

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