Honeywell Error Code E352: Sensor Open
How to Fix Honeywell Code E352
- Step 1: Check the wiring connections at the sensor. If easily accessible and visible, ensure the wires are securely connected. Do not open any sealed compartments or remove any screws.
- Step 2: Check the wiring connections at the control board. Again, if easily accessible and visible, ensure the wires are securely connected. Do not open any sealed compartments or remove any screws.
- Step 3: If the wiring appears secure and the problem persists, contact a qualified HVAC technician to diagnose and repair the system.
How to Reset Honeywell Code E352
- Remove the thermostat from its wall plate.
- Remove the batteries and wait 30 seconds.
- Reinsert the batteries and snap the thermostat back onto the wall plate.
- If the error persists, perform a factory reset through the menu: Menu > Preferences > Restore Factory Defaults.
Resetting clears the code from the display but does not fix the underlying fault. If the code returns after reset, proceed to the diagnostic steps above.
What Does Honeywell Error Code E352 Mean?
The E352 error code on your Honeywell system indicates that the control board has lost communication with one of its temperature sensors. These sensors are used to monitor temperatures at various points in the system, such as the supply water, return water, or outdoor air. When the control board detects an open circuit (meaning the electrical connection is broken) on one of these sensor lines, it triggers the E352 error. This is important because the system relies on these temperature readings to operate safely and efficiently. Without accurate sensor data, the system may not be able to regulate temperature correctly, potentially leading to overheating, freezing, or inefficient operation. The system will likely lock out and require service to restore normal operation.
Common Causes
- Loose or disconnected sensor wiring at the sensor itself or at the control board.
- Damaged sensor wiring due to physical stress, pests, or corrosion.
- Failed temperature sensor (open circuit within the sensor).
- Faulty control board (rare, but possible if the board is not reading the sensor signal correctly).
Diagnostic Steps
| If... | Check | Expected |
|---|---|---|
| System displays E352 error | Measure resistance across the sensor terminals using a multimeter | Resistance should match the sensor's temperature/resistance curve (typically provided in the unit's technical manual). An open circuit (infinite resistance) indicates a failed sensor or wiring issue. |
| Sensor resistance is within range | Check voltage at the control board sensor input terminals with the sensor connected | Typically 5VDC. Absence of voltage suggests a control board problem. |
| Wiring appears intact | Perform a 'wiggle test' on the sensor wiring while monitoring resistance. Gently move the wires to see if the resistance fluctuates, indicating an intermittent connection | Stable resistance reading during the wiggle test. |
Applicable Honeywell Models
Replacement Parts
| Part | OEM Number | Est. Cost | Where to Buy |
|---|---|---|---|
| Temperature Sensor | — | — | — |
| Wiring Harness | — | — | — |
| Control Board | — | — | — |
Related Codes on Same Models
Other codes that affect the same Honeywell model families as E352.
| Code | Description | Severity |
|---|---|---|
| E1 | Communication Error | Warning |
| E2 | Sensor Fault | Warning |
| E3 | EEPROM Error | Warning |
| E350 | Low Battery | Info |
| E351 | Equipment Fault | Warning |
| E353 | Sensor Short | Warning |
| E4 | Short Cycle Protection | Warning |
| E5 | Wiring Error | Warning |