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Not heating: Codes, Causes & Fixes

When a dishwasher, washer, dryer or oven runs but doesn't heat, the usual suspects are the heating element, the temperature sensor (thermistor) that controls it, a safety thermal fuse or – in dryers – restricted airflow that trips the overheat protection. Error codes often distinguish between a sensor fault and a heater circuit fault, which helps decide what to test. Heating elements run on mains voltage, so replacement is a job for a technician unless you are qualified; for boilers see “No heat or hot water”.

71Codes
3.0Average severity
17%High or critical
41%DIY-friendly
Severity distributionSeverity distribution

Most viewed

U4 Daikin · Air Conditioner / Heat Pump The indoor unit has lost its data link with the outdoor unit, so the system can't cool or heat. Moderate E6 Mitsubishi Electric · Air Conditioner / Heat Pump The indoor unit isn't getting valid signals back from the outdoor unit over the S3 wire. Moderate D80 LG · Dryer LG Flow Sense detected restricted airflow in the vent. The dryer still runs, but lint buildup… Moderate HE Samsung · Dryer The Samsung dryer isn’t heating as expected – often no heat at all. Check power, gas supply… Moderate F2 GE Appliances · Oven / Range The control saw the oven running hotter than its safety limit and shut the heat off. High F3 Whirlpool · Oven / Range The control can't get a valid reading from the oven temperature sensor, so it won't heat… Moderate

All codes (61)

All Severity 3+ Severity 4+
11 Fujitsu · Air Conditioner / Heat Pump Error 11: the serial data link on terminal 3 between the Fujitsu indoor and outdoor units has… Moderate 126 Trane · Air Conditioner / Heat Pump 126 on a Trane ComfortLink II thermostat: it lost its data link to the furnace, air handler… Moderate 13 Carrier · Air Conditioner / Heat Pump A limit or rollout switch stayed open too long, so the furnace has locked itself out for 3… High 31 Carrier · Air Conditioner / Heat Pump The inducer couldn't prove a clear vent, so the pressure switch stayed open and the burners… Moderate 33 Carrier · Air Conditioner / Heat Pump A high-temperature safety switch opened, usually because too little air is moving through… Moderate 434 Lennox · Air Conditioner / Heat Pump The Lennox outdoor control can't talk to the inverter drive that runs the variable-speed… Moderate 51 Fujitsu · Air Conditioner / Heat Pump Error 51: the indoor fan ran far slower than commanded for about a minute, so the Fujitsu unit… Moderate A1 Daikin · Air Conditioner / Heat Pump The indoor unit's circuit board couldn't load or apply its settings, so the head refuses to run. Moderate AF Whirlpool · Dryer Whirlpool's vent monitor found restricted airflow: clogged lint screen or vent, or a crushed… Moderate C-21 Samsung · Oven / Range The Samsung range sensed too high an oven temperature – real overheating or a bad sensor… High CH05 LG · Air Conditioner / Heat Pump CH05: the LG indoor unit hears nothing back from the outdoor unit, so the compressor… Moderate CH10 LG · Air Conditioner / Heat Pump CH10: the indoor unit's fan motor isn't turning or isn't reporting its speed, so the unit shuts… Moderate CH21 LG · Air Conditioner / Heat Pump CH21: the outdoor inverter's power module saw a dangerous current peak and cut power… High CH38 LG · Air Conditioner / Heat Pump LG's protection stopped the system because the refrigerant level or pressure looks too low. High D80 LG · Dryer LG Flow Sense detected restricted airflow in the vent. The dryer still runs, but lint buildup… Moderate d90 LG · Dryer LG's duct sensor found a severe exhaust restriction (about 90%). Clean the whole vent before… High d95 LG · Dryer d95 is LG's highest duct-blockage level: about 95% restricted. Don't run more loads until… Critical dHE LG · Washer-Dryer dHE on an LG washer dryer combo: the drying system failed – usually the drying fan motor. Moderate E003 Navien · Water Heater / Boiler The heater sparked and opened its gas valve, but never saw a flame – often a closed valve or no… Moderate E01 Bosch · Dishwasher The main control found a fault in the circuit that powers the heat pump. Start with a breaker… Moderate E012 Navien · Water Heater / Boiler The burner lit, then lost its flame signal mid-cycle – think gas pressure, grounding or a dirty… Moderate E-08 Samsung · Oven / Range The oven didn't warm up to about 100°F within 10 minutes of starting, so the range stopped… Moderate E09 Bosch · Dishwasher The Bosch sees no working heater circuit. On most models the heater is built into… Moderate E09 Bosch · Dryer Bosch lists E09 as an electronic fault for a technician; heat-pump models often have a bad… Moderate E1 Goodman · Air Conditioner / Heat Pump E1: the low-stage pressure switch reads closed before the inducer starts, so the furnace won't… Moderate E1 Gree · Air Conditioner / Heat Pump E1: refrigerant pressure on the high side got too high and the Gree unit stopped the compressor… Moderate E101 Samsung · Air Conditioner / Heat Pump The indoor unit waited too long for the outdoor unit to answer on the F1/F2 link and shut… Moderate E110 Navien · Water Heater / Boiler The fan can't move enough air through the vent system – most often a clogged intake filter… High E201 Samsung · Air Conditioner / Heat Pump E201: after power-up the outdoor unit couldn't find and register its indoor unit(s), so it… Moderate E351 Navien · Water Heater / Boiler Navien combi boilers: the auto make-up water valve couldn't restore heating pressure within 5… Moderate

Symptoms

Won't start a program 55Not cooling 41Leaking water 17Not draining 16Not filling with water 14Door won't lock or open 13No heat or hot water 11Not spinning 9Low system pressure 1