Bosch · Dishwasher
Bosch Dishwasher E20 Error Code
Circulation pump short circuit—~43 ohms expected at pump pins
What this error means
Bosch dishwasher E20 indicates a circulation pump electrical fault—specifically a short circuit or out-of-spec resistance at the pump motor/heater module pins. Service literature cites approximately 43 ohms as the expected reading at the circulation pump connector on heat-pump and standard Bosch sump modules such as SHPM88Z75N and SHEM78B75N. This is NOT Samsung washer E20 or other brands' E20 codes. An impeller jam from glass or seed can mimic E20 by overloading the motor until thermal short detection trips—always clear the filter and rotate the impeller by hand before condemning the pump.
How E20 is detected
Circulation pump on Bosch SHPM88Z75N moves wash water through spray arms and, on heat-pump variants, through the inline heater chamber. E20 latches when the control detects pump circuit resistance below expected—often a shorted motor winding or failed module integrated with heater on some revisions. Measuring ~43 ohms at the pump harness disconnect confirms healthy module; significantly lower ohms indicates short; open circuit indicates break—both store E20 after attempted run.
Mechanical jam diagnosis precedes electrical: remove bottom filter twist-lock, lift pump cover, clear sump, rotate impeller clockwise. A stuck impeller from popcorn kernel or glass shard draws locked-rotor current that trips E20 without permanent pump damage if cleared immediately. Running repeated cycles on a jammed impeller burns the module and raises repair from cleaning to full pump replacement.
Filter and pump cover reassembly follows Bosch E:25 guidance—cover must click fully seated or debris bypasses into the impeller on the next cycle, causing repeat E20. After mechanical verify, access pump connector from beneath toe kick removed; ohm between specified pins with unit unplugged. Compare to ~43 Ω chart for your SHEM78B75N production week.
E20 relates in service history to E09 (heater in same module on heat-pump units), E24 (drain), and E15 (leak wetting connectors). If E15 occurred recently, dry connector boots before ohm test—wet pins read false short. Replacement pump modules vary by integration with heater; match BOM for SHPM88Z75N before ordering—wrong module stores E09 immediately on first heat after install.
Common causes
- Circulation pump motor shorted winding—resistance well below ~43 Ω spec at connector pins
- Impeller jammed by glass, seed, or bone fragment causing locked-rotor overcurrent and E20 latch
- Pump cover not fully seated after filter clean—debris entered impeller and damaged pump
- Moisture in pump connector from E15 base pan event causing false short reading
- Failed integrated heater/pump module shorting combined circuit on heat-pump Bosch units
- Wire harness chafe at sump clamp shorting pump leads to ground
- Control board pump driver damaged—after pump ohms verified at ~43 Ω and impeller free
Step-by-step fixes
- 1Cancel cycle; unplug dishwasher; remove lower rack and twist-lock bottom filter counterclockwise.
- 2Remove pump cover; extract visible debris; rotate impeller clockwise by finger—must spin without grinding.
- 3Reinstall cover until click per E:25; replace filter; restore power; run quick rinse—if E20 cleared, jam was cause.
- 4If E20 returns, unplug; remove toe kick; locate circulation pump harness beneath sump.
- 5Disconnect pump connector; measure ohms between specified pins—expect ~43 Ω; replace module if shorted or open.
- 6Dry connector thoroughly if any base pan moisture present; apply dielectric grease on boot before reconnect.
- 7Install replacement circulation pump matched to SHPM88Z75N/SHEM78B75N BOM; run rinse-only empty; verify no E20 or E09 on heat step.
When to call a technician
Schedule service when ohms confirm pump module failure (~43 Ω not achieved after jam cleared) or when integrated heat-pump module requires cabinet pull on built-in installs. E20 after E15 wetting may need connector harness only—tech can isolate short vs pump. Provide exact model and photo of pump label when ordering; Bosch revised modules across SHPM88Z75N production.
Affected models
- Bosch SHPM88Z75N
- Bosch SHEM78B75N
- Bosch SHX78B75UC
- Bosch SHPM65W55N
- Bosch SHEM63W55N
Prevention & maintenance
- Seat pump cover to click after every filter removal—partial cover is the top impeller jam precursor on Bosch.
- Scrape seeds and pits at sink before loading—impeller jams mimic E20 short before permanent pump damage.
- Dry base pan and pump connector after any E15 leak before running cycles to avoid false E20 from wet pins.