The Bosch E31 error indicates a pressure switch fault, often caused by a clogged pressure hose. To fix it, disconnect the small rubber hose and clear any soap residue or blockages. If the hose is clear, test the pressure switch for continuity while applying air pressure.
While an E31 code points to the water level sensor, technicians often find that the sensor itself is functional. The issue usually stems from debris buildup in the narrow pressure chamber or connecting tube. This guide covers the diagnostic steps required to differentiate between a simple blockage and a failed electronic component, ensuring you do not replace parts unnecessarily.
Bosch dishwashers use a pressure-based water level detection system. A small dome (the air trap or pressure chamber) is connected to the outer tub wall. As water fills the tub, it compresses air in this trapped chamber, increasing pressure on a switch. The switch signals the control board at different pressure thresholds. When the pressure hose is blocked with mineral deposits or soap residue, the chamber cannot sense changing water levels accurately, producing E31.
Most Likely Causes
Based on aggregated repair data, here is the probability breakdown for this error code:
Clogged pressure hose between tub and pressure switch40%
Detergent residue blocking the pressure chamber air trap24%
Wiring issue between pressure switch and control board22%
E31 displayed, dishwasher stops at fill or early wash phase
Dishwasher overfilling or underfilling before E31 appears
E31 with visible appropriate water level in tub
Intermittent E31 that clears with reset
Can you reset a Bosch dishwasher to clear the E31 code?
After cleaning the pressure hose or replacing the switch, hold Start/Reset for 5 seconds and run a test cycle to confirm E31 is cleared.
Tools Required for Diagnosis
MultimeterPipe cleaner or thin wireWhite vinegarFlathead screwdriver
Diagnostic Checklist
Follow these steps in order. We start with the easiest external fixes before opening up the machine.
Replacement Parts
If your diagnostic testing proves the component has failed, you will need a replacement. We recommend OEM parts over aftermarket for water-handling components.
Part Name
OEM Number
Estimated Price
Pressure Switch / Water Level Switch00425928 · $20–$45
00425928
$20 – $45
Frequently Asked Questions
Where is the pressure sensor on a Bosch dishwasher?
The pressure switch on a Bosch dishwasher is located near the bottom of the tub, typically mounted on the side wall of the inner cabinet or accessible behind the kick plate panel at the front bottom. It is connected to the tub via a thin rubber hose that runs to an air trap dome at the tub base. The switch itself is a small round or rectangular component with 2-3 wires connected to it. On most models it is accessible without fully pulling the dishwasher from the cabinet.
Can I clean the pressure chamber myself to fix E31?
Yes, and cleaning the pressure hose and air trap should be the first repair step before buying any parts. The procedure requires no special tools - just a pipe cleaner, white vinegar, and about 45 minutes. Disconnect power and water, remove the hose from the switch and tub ends, soak it in vinegar for 30 minutes, flush with water, and confirm air flows freely through it before reinstalling. This free fix resolves E31 in a large percentage of cases, particularly on dishwashers more than 5 years old.
I have E31 and the dishwasher won't fill - are they related?
Yes, they are related. If the pressure switch reads no water (because its hose is blocked), the control board may interpret this as the tub being empty even when water is present, preventing it from advancing through the fill phase. Alternatively, if the switch is stuck reading a full tub, the fill valve will not open because the board thinks sufficient water is already present. Either way, cleaning the pressure hose is the correct first diagnostic step before chasing a fill valve problem.
How do I do the blow test on a Bosch pressure switch?
Disconnect the rubber hose from the switch inlet port. Set a multimeter to continuity mode. Place the probes on the switch terminals (the common pin and the normally-closed pin). Blow a short firm puff of air directly into the switch inlet port - the switch should make an audible click and the multimeter continuity reading should change from closed to open. Release and the circuit should return to closed with another click. If no click occurs or the multimeter reading does not change, the switch diaphragm or contacts have failed and the switch needs replacement.
How often should the pressure hose be cleaned on a Bosch dishwasher?
Bosch does not publish a specific cleaning interval for the pressure hose, but in hard-water areas, a cleaning every 3-4 years is a practical preventive measure. The hose is most likely to clog if you use powdered detergent (which leaves more residue than gel or pod detergents) or if your water supply has high mineral content (above 120 mg/L calcium carbonate). If you receive an E31 code and cleaning resolves it, that is a signal to add the procedure to your maintenance schedule going forward.