Dometic ProHeat X45 Flame Sensor
The Dometic ProHeat 954329K Flame Sensor is the factory replacement flame-detection sensor used in ProHeat X45 and X45 Plus diesel-fired coolant heaters.
Unlike a temperature-based sensor, the ProHeat flame sensor is an optical device that detects the presence of the combustion flame. During startup, the heater’s control system uses the flame sensor to confirm that ignition has occurred before transitioning to normal operation.
Key Features
- Genuine Dometic ProHeat replacement component
- Factory part number 954329K
- Fits ProHeat X45
- Fits ProHeat X45 Plus
- Optical flame-detection sensor
- Monitors flame during ignition and heater operation
- Supports Start and Flame-Out diagnostics
- Used with both 12V and 24V X45 heater configurations
- Included in the PK0069 X45 Major Service Kit
- Documented in select legacy ProHeat XL-Series heaters
How the Flame Sensor Works
When the ProHeat heater starts, the blower, coolant pump, ignition system, compressor, and fuel system begin their startup sequence.
The flame sensor watches for successful combustion. Once it detects a stable flame, the heater can transition from ignition into full-output operation.
The sensor also continues monitoring flame during operation. If the heater loses combustion, the control system can attempt to re-establish the flame and generate a diagnostic fault if combustion cannot be restored.
X45 Diagnostic Functions
The flame sensor is directly involved in several ProHeat diagnostic functions.
Start Fault
A Start fault can occur when the flame sensor does not detect a sufficient flame during the ignition period.
Possible causes can include:
- Fuel-delivery problems
- Ignition-system problems
- Poor combustion
- Dirty flame sensor lens
- Failed flame sensor
Flame-Out Fault
A Flame Out fault indicates that a flame was initially detected but was later lost or could no longer be detected during operation.
ProHeat notes that a dirty flame sensor can contribute to this condition.
Flame Sensor Diagnostic
On X45 Plus systems, the flame sensor is identified as Component Diagnostic Code 6. A flame-sensor fault can indicate problems such as a sensor failure, wiring fault, or an unexpected flame signal.
Compatibility
- Manufacturer: Dometic ProHeat
- ProHeat Part Number: 954329K
- BTRAC Part Number: PH-954329K
- Product Type: Optical Flame Sensor
- Compatible Heater: ProHeat X45
- Compatible Heater: ProHeat X45 Plus
- System: Combustion / flame detection
- Voltage Specific: No separate 12V/24V sensor listed
The official X45 Plus parts catalog identifies 954329K as Item 2 – Sensor, Flame in the fan-end assembly.
Legacy ProHeat XL-Series Applications
ProHeat’s factory XL service-parts catalog also documents the 954329 flame sensor in several legacy heaters, including:
- XL900 Mark I
- XL900 Mark II
- XL1500 Mark II
The XL900 Mark I catalog lists the same flame-sensor number as well.
Because the legacy XL literature commonly lists the number as 954329 without the modern K suffix, verify the existing sensor and heater model before ordering for an XL-Series application.
Included in the X45 Major Service Kit
The 954329K Flame Sensor is included in the factory PK0069 X45 Major Service Kit.
That kit includes:
- 880035K – Fuel Filter with two O-rings
- 825730K – Compressor Air Filter
- 951126K – Fuel Regulator
- 930523K – Ignition Lead
- 954329K – Flame Sensor
- 938326K – Fuel Nozzle with O-ring
- 933525K – Igniter with gasket
- Major service instructions
Maintenance and Cleaning
A dirty sensor does not necessarily mean the sensor has failed.
ProHeat recommends inspecting the flame-sensor glass as part of heater maintenance. To maintain proper sensor readings:
- Inspect the sensor glass for contamination
- Wipe the glass clean using water and a rag
- Make sure the glass is clear before reassembly
- Inspect the wiring and connector for damage
- Test heater operation after service
ProHeat specifically notes that contamination on the optical surface can prevent the sensor from properly detecting the flame.
Installation Notes
Before replacing the flame sensor:
- Shut the heater down completely
- Allow the heater to cool
- Disconnect electrical power
- Inspect the sensor wiring and connector
- Inspect and clean the existing sensor lens before condemning the sensor
- Check the ignition and fuel systems if Start or Flame-Out faults are present
- Install the replacement sensor according to ProHeat service procedures
- Confirm proper heater startup and operation after installation
Because several fuel, ignition, and combustion problems can produce similar symptoms, ProHeat recommends diagnosing the heater before replacing individual components.
Product Specifications
- BTRAC SKU: PH-954329K
- Manufacturer: Dometic ProHeat
- Manufacturer Part Number: 954329K
- Product Type: Flame Sensor
- Sensor Type: Optical
- Compatible Heater: ProHeat X45
- Compatible Heater: ProHeat X45 Plus
- Legacy Applications: Select XL900 and XL1500 heaters
- System: Combustion / flame detection
- X45 Plus Diagnostic Code: 6
- Included in PK0069 Major Service Kit: Yes
- Application: Replacement / service component
Related ProHeat Parts
- PH-933525K – X45/X45 Plus Igniter
- PH-930523K – Ignition Lead
- PH-938326K – Fuel Nozzle
- PH-951126K – Fuel Regulator
- PH-825730K – Compressor Air Filter
- PH-880035K – Fuel Filter
- PK0069 – X45/X45 Plus Major Service Kit
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