Husqvarna 531008615 NGK CMR6H Spark Plug – Genuine OEM Replacement Spark Plug
Part Number: 531008615
Category: Engine Ignition, Tune-Up & Spark Plug Components
Type: NGK CMR6H Spark Plug – Genuine OEM Replacement Spark Plug
The Husqvarna 531008615 NGK CMR6H Spark Plug is a genuine OEM replacement ignition component designed for a wide range of compatible Husqvarna chainsaws, string trimmers, brushcutters, hedge trimmers, and other outdoor power equipment. The plug threads directly into the engine cylinder and produces the electrical spark required to ignite the compressed air-fuel mixture inside the combustion chamber.
Product Specifications
- Part Number: 531008615
- Manufacturer: Husqvarna
- Spark Plug Manufacturer: NGK
- Spark Plug Model: CMR6H
- Product Type: Spark Plug
- OEM Description: CMR6H NGK Spark Plug
- Component Type: Engine Ignition Component
- Function: Creates the Spark Required to Ignite the Air-Fuel Mixture
- Application: Outdoor Power Equipment
- Compatible Brand: Husqvarna
- Additional OEM Applications: Select Jonsered / RedMax / Ryobi Equipment
- Thread Diameter: 10 mm
- Thread Reach: 12.7 mm
- Hex Size: 16 mm
- Seat Type: Flat
- Terminal Type: Solid
- Tip Configuration: Non-Projected
- Construction: Standard
- NGK Stock Number: 3365
- Component Location: Engine Cylinder / Combustion Chamber
- System: Ignition / Engine
- Replacement Type: Direct OEM Replacement
- OEM Status: Genuine Husqvarna OEM Replacement Part
- Condition: New
- Quantity: 1 Spark Plug
- Part Number Reference: 531008615
- Alternate Number Format: 531 00 86-15
- UPC: 705788542659
The dimensional and construction specifications above are documented for Husqvarna 531008615 / NGK CMR6H, and genuine-parts references list UPC 705788542659.
Features & Benefits
- Genuine Husqvarna OEM replacement spark plug
- Manufactured by NGK
- Genuine CMR6H specification
- Designed for compatible Husqvarna outdoor power equipment
- Provides the electrical spark required for combustion
- Supports reliable engine starting
- Helps maintain consistent ignition
- Supports efficient combustion when properly maintained
- 10 mm threaded design
- 12.7 mm thread reach
- 16 mm hex
- Flat-seat configuration
- Solid terminal
- Non-projected tip
- Suitable for routine engine tune-ups and maintenance
- Direct replacement for multiple earlier Husqvarna spark-plug numbers
- Used across compatible chainsaws, trimmers, brushcutters, hedge trimmers, and other equipment
Documented Husqvarna Applications
The 531008615 CMR6H Spark Plug is documented for numerous Husqvarna models and series, including select:
- Husqvarna 224L
- Husqvarna 324HDA55X
- Husqvarna 324LDX
- Husqvarna 324LX
- Husqvarna 324RX
- Husqvarna 439
- Husqvarna 524 Series
- Husqvarna 545
- Husqvarna 545FX
- Husqvarna 545FXT
- Husqvarna 545RX
- Husqvarna 545RXT
- Husqvarna 550 XP
- Husqvarna 550 XP Mark II
- Husqvarna 550 XP G Mark II
- Husqvarna 555
- Husqvarna 560 XP
- Husqvarna 562 XP
- Husqvarna 585
- Husqvarna 592 XP
- Husqvarna T435
- Husqvarna T540 XP
- Husqvarna T540 XP II
- Select additional Husqvarna chainsaws
- Select Husqvarna trimmers and brushcutters
- Select Husqvarna hedge trimmers
- Select Husqvarna blowers
Current Husqvarna information also identifies the NGK CMR6H for equipment including the 550 XP Mark II, T435, T540 XP, 545, 555, 560 XP, 562 XP, 585, 592 XP, 350BT, 580BTS, and numerous other models.
Exact compatibility should always be confirmed using the complete equipment model, product number, engine configuration, and production revision.
Spark Plug Function
The spark plug is one of the central components of a gasoline engine's ignition system.
During operation, the 531008615 CMR6H Spark Plug:
- Receives high-voltage electrical energy from the ignition system
- Produces an electrical arc across its electrode gap
- Ignites the compressed air-fuel mixture
- Initiates combustion
- Supports repeated combustion cycles as the engine operates
Replacement-parts documentation confirms that 531008615 screws into the cylinder and creates the electrical arc that ignites the fuel-air mixture inside the combustion chamber.
Superseded & Cross-Reference Numbers
The Husqvarna 531008615 replaces several earlier Husqvarna spark-plug references, including:
- 514543001
- 5145430-01
- 521233501
- 5212335-01
- 574519601
- 5745196-01
- 590843801
Both 521233501 and 574519601 are specifically documented as superseded to 531008615.
Additional spark-plug references associated with the CMR6H specification include:
- NGK CMR6H
- NGK 3365
- Honda 31916-Z0H-003
- Bosch USR7AC
- Champion RZ7C
Always verify equivalency for the specific engine before substituting another manufacturer's plug.
Common Reasons for Replacement
Replacement of the 531008615 NGK CMR6H Spark Plug may be appropriate if the existing plug has:
- Become carbon fouled
- Developed worn electrodes
- Become oil fouled
- Developed excessive deposits
- Sustained physical damage
- Developed a cracked insulator
- Become corroded
- Developed an incorrect or excessive electrode gap
- Reached the manufacturer's recommended maintenance interval
- Become unable to provide reliable ignition
Spark plugs naturally experience electrode wear because they operate directly within the combustion environment. Carbon buildup, overheating, and contamination can accelerate deterioration.
Possible Signs of a Worn Spark Plug
A worn or fouled spark plug may contribute to:
- Difficult starting
- Engine misfires
- Rough running
- Unstable idle
- Poor acceleration
- Reduced engine power
- Intermittent ignition
- Engine stalling
- Increased starting attempts
- Poor combustion
These symptoms can also result from carburetor, fuel-system, compression, ignition-module, air-filter, or other engine problems, so proper diagnosis is recommended.
Spark Plug Inspection
When servicing the spark plug, inspect the:
- Center electrode
- Ground electrode
- Ceramic insulator
- Terminal
- Threads
- Electrode gap
- Spark plug boot
- Ignition lead
- Cylinder-head threads
The condition of the old spark plug can also provide useful information about combustion and engine condition.
Installation
A spark plug wrench is required for removal and installation on applicable equipment.
When replacing the spark plug:
- Shut off the engine and allow it to cool.
- Disconnect the spark plug boot.
- Clean debris from around the spark plug opening.
- Remove the existing plug using the appropriate spark plug wrench.
- Inspect the old plug for abnormal deposits or damage.
- Verify the replacement plug specification and electrode gap.
- Thread the new plug into the cylinder carefully by hand initially.
- Tighten it according to the applicable Husqvarna service specification.
- Reinstall the spark plug boot securely.
- Start the engine and verify normal operation.
Important Notes
- Verify compatibility with your exact Husqvarna equipment model, product number, serial number, and engine configuration before ordering.
- Match part number 531008615 or the specified NGK CMR6H plug with your equipment documentation.
- The OEM description is “CMR6H NGK Spark Plug.”
- The plug has a 10 mm thread diameter, 12.7 mm thread reach, and 16 mm hex.
- The seat type is flat and the tip configuration is non-projected.
- NGK stock/reference number for the CMR6H is 3365.
- 521233501 is a documented previous Husqvarna part number superseded by 531008615.
- 574519601 is also documented as superseded by 531008615.
- Additional replacement references include 514543001 and 590843801.
- Do not select a spark plug based solely on thread diameter or physical appearance.
- Spark plugs can differ in thread reach, heat range, resistor design, electrode configuration, seat style, and required gap.
- Using an incorrect spark plug can cause poor engine performance and potentially result in engine damage.
- Always use the spark plug type specified for the exact engine.
- Check the electrode gap before installation and adjust only according to the applicable equipment manufacturer's specification.
- Do not assume one gap specification applies to every engine using a CMR6H plug.
- Never force the spark plug into the cylinder-head threads.
- Start installation by hand to reduce the risk of cross-threading.
- Do not overtighten the plug.
- Inspect the spark plug boot and ignition lead for damage while servicing the plug.
- Keep dirt and debris from entering the cylinder while the plug is removed.
- Allow the engine to cool before removing the spark plug.
- A recently operated spark plug, cylinder, and muffler can be extremely hot.
- If a replacement plug quickly becomes fouled again, inspect the engine and fuel system for an underlying problem.
- This listing is for one Husqvarna 531008615 NGK CMR6H Spark Plug only unless otherwise specified.
- Match Husqvarna 531008615 / NGK CMR6H with your equipment's OEM documentation before ordering to ensure proper fitment.
