2021-2026 Honda Civic Oil Leak at Timing Chain Tensioner

Honda has released Service Bulletin 25-076, dated July 28, 2025, to address concerns regarding an oil leak at timing chain tensioner inspection cover in certain 2021-2026 Honda Civic vehicles equipped with the 1.5L Turbo engine. This bulletin provides technicians with detailed diagnostic and repair procedures for this specific issue. If you notice a Honda Civic oil leak, this bulletin outlines the steps your dealer will take.

Symptoms of a Honda Civic Oil Leak

The primary symptom owners may observe is an oil leak at timing chain tensioner inspection cover. This can manifest as visible oil stains or drips under the vehicle, particularly around the front of the engine where the timing chain is located.

Why Your Honda Civic Might Be Leaking Oil

According to Honda, the most probable cause for this specific Honda Civic oil leak is insufficient sealant adhesion on the timing chain tensioner inspection cover. Over time, the factory sealant may degrade or fail to provide a complete seal, allowing engine oil to escape.

Important Owner Information

Honda emphasizes that the information contained within Service Bulletin 25-076 is intended solely for use by skilled technicians who possess the proper tools, equipment, and training. These procedures should not be attempted by "do-it-yourselfers," and you should not assume this bulletin applies to your vehicle, or that your vehicle has the condition described. To determine whether this information applies to your vehicle, it is recommended to contact an authorized Honda automobile dealer.

Diagnosing the Oil Leak

To accurately identify the source of the oil leak, technicians will perform an engine oil leak diagnostic using the specialized Honda Leak Detection Kit. The diagnostic process involves several steps:

1. The engine is turned off, and the engine cover (if present) is removed.
2. Metal pliers are used to pinch off the breather tube, and plastic pliers are used to pinch off the PCV tube.
3. The engine oil dipstick is removed.
4. A specialized fitting (C) is inserted into the engine oil level dipstick hole, ensuring it engages correctly.
5. An air pump hose is connected to the fitting and then to the supplied air pump.
6. The air pump is activated, and after two minutes, the crankcase is checked for air pressure by listening for a release of pressure when the fitting is pulled slightly from the dipstick tube. If no pressure is heard, the technician will verify proper pinching and blocking of hoses before retesting.
7. The right front wheel and underbody splash shield are removed to gain access to the timing chain tensioner inspection cover.
8. The suspected oil leak area is sprayed with soapy water.
9. Technicians then look for air bubbles, which confirm the presence and location of a leak. If a leak is found at the Cam Chain Tensioner Inspection Cover, the repair procedure is initiated. If another leak source is identified, further troubleshooting will be performed.

Repair Procedure Summary

Once a leak is confirmed at the timing chain tensioner inspection cover, technicians will follow these steps:

1. The timing chain tensioner inspection cover is carefully removed.
2. Any old sealant is thoroughly removed from both the timing chain cover and the inspection cover using a scouring pad.
3. A new 2.5 mm bead of sealant, specifically Hondabond HT Silicone Gasket (part number 08718-0004), is applied to the inspection cover.
4. The inspection cover must be reinstalled within four minutes of applying the new sealant.
5. The cover bolts are torqued to 9 lb-ft.
6. Finally, the Engine Oil Leak Detection Kit is removed, and all previously removed parts are reinstalled in reverse order.

Required Tools and Parts

To perform the diagnostic and repair outlined in TSB 25-076, specific tools and materials are required:

• Leak Detection Kit: Part Number 07AAJ-5A2A100
• Hondabond HT Silicone Gasket: Part Number 08718-0004 (one tube is sufficient for approximately five repairs)
• Cover, Chain Case: Part Number 11412-59B-000 (only ordered if the original cover is damaged and requires replacement)

Warranty Information

For authorized Honda dealers, warranty claims related to this service bulletin should use the following information:

• For diagnosing and re-sealing the timing chain inspection cover:
  • Operation Number: 1107A3
  • Flat Rate Time: 0.6 hours
  • Defect Code: 07408
  • Symptom Code: 05101
  • Template ID: A25076A
  • Failed Part Number: 11412-59B-000
• For diagnosing and replacing the timing chain inspection cover:
  • Operation Number: 1101KH
  • Flat Rate Time: 0.6 hours
  • Defect Code: 07408
  • Symptom Code: 05101
  • Template ID: A25076B
  • Failed Part Number: 11412-59B-000

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Source: NHTSA ID: 11021745, Service Bulletin 25-076.