Quick symptom overview
Bosch 800 Series, Benchmark, and B26/B36 built-in or freestanding French-door refrigerators post E10 or E11 when the main power module detects an out-of-range temperature sensor signal or an open defrost heating loop.
Bosch climate control relies on a 5 kΩ class NTC thermistor and 120 VAC defrost loop: Power module (11032338) → NTC temperature sensors (00619280 / 00619282, ~5 kΩ at 77°F) → 120 VAC defrost heater (00774381, ~30–50 Ω) → inline thermal safety fuse (00619283, ~0 Ω) → power module return. E10 monitors the fresh-food evaporator NTC sensor; E11 monitors the freezer evaporator NTC sensor and verifies defrost loop continuity during automatic defrost cycles.
E10 displayed with warm fresh-food compartment: Open or shorted fresh-food NTC sensor, damaged sensor wire, or corroded PCB connector. E11 displayed with heavy frost on freezer evaporator: Open defrost heater element (∞ Ω), blown thermal fuse (~0 Ω normal, ∞ Ω open), or failed freezer NTC sensor. Related refrigerator cooling diagnostics: LG refrigerator warm fresh food troubleshooting. Inverter compressor vs board testing: Inverter refrigerator linear compressor vs control board checks. Brand service details: Bosch refrigerator repair services.
Safety: Unplug the refrigerator or disconnect the main circuit breaker before removing evaporator cover plates or probing main power module connectors. Aluminum evaporator fins are thin and sharp—wear cut-resistant gloves. Never use metal ice picks or heat guns on high setting to melt coil frost, as heat deforms plastic liner walls and ruptures aluminum coils.
Step-by-step diagnostic hierarchy
-
Confirm display code and compartment temperatures — Record whether E10 or E11 is active. Place thermometers in both compartments:
- Fresh food warm (> 45°F), freezer normal (0°F) + E10: Fresh-food evaporator NTC sensor or damper path.
- Both sections warming, heavy frost visible through rear freezer vents + E11: Freezer defrost heater element, thermal fuse, or freezer NTC sensor.
-
Access power module thermistor header (Power OFF) — Unplug the refrigerator. Remove the rear lower compressor compartment shield or top control housing (model specific) to access the main power module board (11032338).
-
Measure NTC temperature sensor resistance (Ohms) — Disconnect the multi-pin NTC sensor harness from the power module. Measure resistance across the two sensor pins for each channel:
- Fresh Food Evaporator NTC (E10 path):
- At 77°F (25°C): 4.8–5.2 kΩ
- At 32°F (0°C ice water test): ~16.3 kΩ
- Freezer Evaporator NTC (E11 path):
- At 0°F (-18°C operational temp): 32.0–36.0 kΩ
- At 77°F (25°C room temp): 4.8–5.2 kΩ
- Open sensor: Reads ∞ Ω (causes immediate E10 or E11 code).
- Shorted sensor: Reads 0–100 Ω (shorted probe wires).
- If sensor resistance strays off the NTC curve by > 10%, replace NTC thermistor 00619280 / 00619282.
- Fresh Food Evaporator NTC (E10 path):
-
Examine freezer evaporator coil and frost pattern — Remove freezer interior drawers and the rear plastic evaporator cover plate:
- Heavy solid ice block across all fins: Complete defrost failure (E11 heater or fuse fault).
- Frost localized to top 1–2 turns only: Sealed-system refrigerant leak or low charge.
-
Test defrost heater element resistance (00774381) — Disconnect the 2-pin defrost heater connector on the side of the evaporator coil:
- Measure resistance across the heater terminals using multimeter 200 Ω range.
- Normal cal-rod / glass heater: Must read 30–50 Ω.
- Open heater element: Reads ∞ Ω (replace defrost heater assembly).
-
Test inline defrost thermal safety fuse (00619283) — Locate the inline thermal fuse clipped to the top turn of the evaporator coil:
- Disconnect thermal fuse leads and test continuity:
- Normal thermal fuse at room temp: Must read ~0 Ω (closed circuit).
- Blown thermal fuse: Reads ∞ Ω (open circuit due to prior overheat > 160°F).
- If the fuse is open (∞ Ω), replace the thermal fuse harness 00619283.
- Disconnect thermal fuse leads and test continuity:
-
Verify 120 VAC defrost power call from main PCB (Live Test) — Reconnect heater and fuse. Reapply power, enter Bosch service mode (Press Super + Alarm buttons per tech sheet), and command a forced defrost:
- Measure voltage across the main PCB defrost relay output terminals:
- Expected voltage: 120 VAC.
- No 120 VAC output with good NTC sensors and good heater loop indicates a failed defrost relay on main power module 11032338.
- Measure voltage across the main PCB defrost relay output terminals:
Multimeter and safety checks
Disconnect power before measuring resistance (Ohms) on sensor or heater components.
| Component / Test | Setup & Meter Range | Expected Normal Value | Fault / Failure Mode |
|---|---|---|---|
| NTC Sensor @ 77°F | Isolated NTC plug, 20 kΩ range | 4.8–5.2 kΩ | ∞ Ω (open; triggers E10 / E11) or < 100 Ω (shorted) |
| NTC Sensor @ 32°F | Sensor in ice water, 20 kΩ range | ~16.3 kΩ | Out of spec resistance curve |
| NTC Sensor @ 0°F | Cold freezer sensor, 200 kΩ range | 32.0–36.0 kΩ | Resistance drifted off curve |
| Defrost Heater (00774381) | Isolated heater plug, 200 Ω range | 30–50 Ω | ∞ Ω (open element; causes E11) |
| Thermal Fuse (00619283) | Isolated fuse leads, 200 Ω range | ~0 Ω | ∞ Ω (open safety fuse from overheat) |
| Heater Wire to Chassis | Terminal pin to cabinet, 2 MΩ range | ∞ Ω | < 1 MΩ (shorted heater to ground; trips GFCI) |
| PCB Defrost Output | Live test during forced defrost, 200 VAC | 120 VAC | 0 VAC (failed defrost relay on power module) |
Root cause vs repair breakdown
| Observable Symptom | Root Cause / Faulty Part | Corrective Repair Action |
|---|---|---|
| E10 on display, fresh food section warm | Open/shorted fresh food NTC sensor (00619280) | Replace fresh food evaporator NTC sensor probe |
| E11 on display, heavy ice on freezer coil | Open defrost heater (00774381) or blown thermal fuse | Replace defrost heater or thermal fuse assembly |
| NTC sensor reads 5 kΩ at 77°F, E11 still active | Open freezer NTC sensor wire or bad PCB header | Repair harness connection or replace power module |
| Heater (35 Ω) and fuse (0 Ω) test good, no 120 VAC | Failed defrost relay on main PCB (11032338) | Replace main power module board assembly |
FAQ
What do E10 and E11 mean on a Bosch refrigerator?
E10 indicates a fresh food evaporator NTC temperature sensor fault (open or shorted sensor). E11 indicates a freezer evaporator NTC temperature sensor or defrost heater circuit fault (open 120 VAC heater, blown thermal fuse, or out-of-spec 5 kΩ NTC thermistor 00619280).
How do I test a Bosch refrigerator NTC temperature sensor with a multimeter?
Unplug the refrigerator. Disconnect the NTC sensor plug at the main power module or evaporator harness. Measure resistance across the two sensor pins: a good Bosch 5 kΩ class NTC sensor reads ~4.8–5.2 kΩ at 77°F (25°C), ~16.3 kΩ at 32°F (0°C), and ~32–36 kΩ at 0°F (-18°C).
What should the defrost heater read on a Bosch refrigerator?
Isolate the defrost heater connector on the rear evaporator coil housing. A functional 120 VAC cal-rod or glass defrost heater (00774381) reads ~30–50 Ω. An open heater (∞ Ω) or blown inline thermal fuse (~0 Ω normal, ∞ Ω open) prevents automatic defrost and triggers E11.
When to schedule professional service
If electrical testing requires live 120 VAC measurements inside the power module box, or forced defrost coil steam clearing and sealed system verification is needed, professional service is recommended. Schedule Bosch refrigerator repair →
FAQ · Family-owned Port St. Lucie
Frequently Asked Questions About Bosch Refrigerator E10 / E11
What do E10 and E11 mean on a Bosch refrigerator?
E10 indicates a fresh food evaporator NTC temperature sensor fault (open or shorted sensor). E11 indicates a freezer evaporator NTC temperature sensor or defrost heater circuit fault (open 120 VAC heater, blown thermal fuse, or out-of-spec 5 kΩ NTC thermistor 00619280).
How do I test a Bosch refrigerator NTC temperature sensor with a multimeter?
Unplug the refrigerator. Disconnect the NTC sensor plug at the main power module or evaporator harness. Measure resistance across the two sensor pins: a good Bosch 5 kΩ class NTC sensor reads ~4.8–5.2 kΩ at 77°F (25°C), ~16.3 kΩ at 32°F (0°C), and ~32–36 kΩ at 0°F (-18°C).
What should the defrost heater read on a Bosch refrigerator?
Isolate the defrost heater connector on the rear evaporator coil housing. A functional 120 VAC cal-rod or glass defrost heater (00774381) reads ~30–50 Ω. An open heater (∞ Ω) or blown inline thermal fuse (~0 Ω normal, ∞ Ω open) prevents automatic defrost and triggers E11.