WWP-99 Engine Cylinder Head Coolant Leaks

June 10, 2011. Author:

1. WWP-99 SUBARU Owner Notification Letter

This letter is kind of long, so here is a link to the full text ( also included at the end of this document for reference ).

2. Technical Service Bulletin WWP-99

NUMBER: WWP-99               DATE: 02/2004


2000-2002 Model Year Subaru Legacy and Outback;
1999-2002 Model Year Impreza
1999-2002 Model Year Forester

SUBJECT: Engine Cooling System Conditioner


Subaru of America, Inc. (SOA) has determined that over time, affected vehicles may develop small external coolant leaks at engine cylinder head gaskets. This is the result of normal expansion and contraction of engine components caused by the heating and cooling of these parts. To prevent cylinder head gasket leaks from developing or to correct existing leaks, a special Subaru Cooling System Conditioner should be added to affected vehicle cooling systems.

This Service Program will involve adding one bottle of Genuine Subaru Cooling System Conditioner to the engine cooling system.


  • 2000-2002 MY Subaru Legacy and Outback with 2.5L engine.
  • 1999-2002 MY Impreza with 2.5L engine.
  • 1999-2002 MY Forester with 2.5L engine.

Affected vehicles are identified in the VIN range chart below. Only vehicles with a 2.5L engine are affected.


Model  FromTo
  Outback WagonY*600001Y*674127
  Outback Wagon1*6000011*679753
  Outback Wagon2*6000012*605593


NOTE: Prior to performing repairs, confirm coverage for potentially affected vehicles by using the Vehicle Coverage Inquiry in the Dealer Communication System (DCS).

Vehicles identified in the preceding chart may include VINs that were not distributed in the U.S. market. Dealers will be provided a list of VINs that include the owner name and address. This information will enable dealers follow-up with owners of potentially affected vehicles. These listings contain owners names and addresses obtained from State Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is unlawful. Accordingly dealers are urged to limit the use of this listing only for the purpose of completion of this service program.


SOA prepare and mail an Owner Notification Letter to owners of the affected vehicles. Because of the number of vehicles affected and parts availability, owner notification will occur on or about the dates listed in the following four stages.

1999 MY - February 16, 2004
2000 MY - March 1, 2004
2001 MY - April 1, 2004
2002 MY - May 3, 2004

A copy of the owner notification letter is included at the end of this bulletin.


Owners are being advised in the owner notification letter, found at the end of this bulletin, that if they have previously paid an authorized Subaru dealer for repairs related to this Service Program, they may be entitled to reimbursement. The owners are further advised, to qualify for any reimbursement they must submit the original repair invoice to Subaru of America, Inc. Please review the owner notification letter, which explains this procedure so that you are familiar with it, and can assist owners with any questions.


In the future, it will be necessary to add Genuine Subaru Coding System Conditioner to the coding system of affected vehicles whenever the engine coolant is replaced. As a reminder, owners will be sent update pages with their notification letter that instructs them to add the pages to their Owner's Manual and Warranty and Maintenance Booklet Except for the initial application associated with this campaign, the cost of adding the conditioner is the owner's responsibility.


For owners of affected vehicles that have this Service Program performed promptly, SOA is extending coverage under the Subaru Limited Warranty for cylinder head gasket external coolant leaks to a period of 8 years or 100,000 miles, whichever occurs first Warranty coverage begins on the date the vehicle was delivered to the first retail purchaser. If the vehicle was used as a demonstrator or company vehicle before being sold at retail, warranty coverage begins on the date the vehicle was first placed in such service.

As a further condition for this extended warranty coverage to apply, the owner must properly maintain the vehicle's cooling system in accordance with the recommended maintenance schedule and Genuine Subaru Cooling System Conditioner must be added each time the engine coolant is replaced. Resulting damage caused by a lack of maintenance or low coolant level will not be covered. Replacement of the Cooling System Conditioner during inspection and maintenance services is not covered under warranty.


Dealers are to promptly service vehicles subject to this Service Program at no charge to the vehicle owner regardless of mileage, age of the vehicle, or ownership.

For affected vehicles sold after the date on the dealer's computer list, dealers are to contact those owners and provide them with a copy of the owner notification letter. They should also arrange to make the required correction according to the instructions in the service procedure section of this bulletin.

 MODEL: ALL    DESCRIPTION: Subaru Cooling System Conditioner (Case Quantity)   Part # SOA345001

Vehicles in Dealer Inventory

Dealers are also to promptly perform the applicable service procedures defined in this bulletin to correct affected vehicles in their inventory (new, used, demo). Additionally, whenever a vehicle subject to this Service Program is taken into dealer new or used inventory, or is in the dealership for service, necessary steps should be taken to ensure the Service Program correction has been made before selling or releasing the vehicle.

New or used vehicles listed in a recall/campaign that are in dealer stock must be:

  • Immediately identified.
  • Tagged or otherwise marked to prevent their delivery or use prior to inspection and/or repair.
  • Inspected and/or repaired in accordance with instructions outlined in the Product Campaign Bulletin. 

Any Authorized Subaru Dealer failing to perform the applicable service procedures defined in this bulletin to correct affected vehicles in their inventory (new, used, demo) prior to the vehicle being placed in service may be in breach of the Subaru Dealer Agreement.


Subaru Cooling System Conditioner

Note :Subaru Cooling System Conditioner is packaged in cases that contain 12 bottles. Each affected vehicle requires one (1) bottle. Each case contains enough material to treat 12 vehicles.

Prior to the release of this Service Program, each dealer will automatically be shipped a quantity of Subaru Cooling System Conditioner equivalent to 40% of their vehicle sales, or up to a maximum of 20 cases.

Additional quantities of the Cooling System Conditioner will be available through normal parts channels after 2/15/04. In order to maintain an adequate part supply, SOA requests that Dealers only order quantities necessary to satisfy anticipated demand.


The repair procedure involves adding Subaru Cooling System Conditioner to the cooling system. Follow the recommended procedure that applies to either a "Cold" or "Hot" engine.

Caution :The engine cooling system is under pressure and may he extremely hot. To prevent personal injury or vehicle damage he sure to take appropriate precautions while performing this procedure.

Service Procedure on a COLD Engine

1. Install rags around the radiator filler neck to prevent coolant from contaminating the engine area.

2. Take off the radiator cap and set aside.

3. Extract 125ml (4.23 oz.) of coolant from the radiator using a suitable device such as a piston syringe, meat or poultry baster, antifreeze hydrometer, etc.

4. Place the syringe into the overflow reservoir and push the coolant out of the syringe.
5. Shake the bottle of cooling system conditioner until all contents are thoroughly mixed.
6. Pour the entire bottle of cooling system conditioner into the radiator.
NOTE :Do NOT pour the cooling system conditioner into the overflow reservoir. The conditioner Will settle at the bottom of the reservoir and not mix in the cooling system.

7. Reinstall the original radiator cap.
8. Remove rags from around the radiator filler neck.
9. Start the vehicle and let it run until the engine is warm. This ensures the conditioner circulates and there are no air pockets in the cooling system. 

Service Procedure on a HOT Engine

1. Turn the ignition key to the "ON" position (engine off).
2. Turn the air conditioning "ON" to cycle the cooling fans. Leave the air conditioning "ON" for approximately two (2) minutes. This will lower the pressure in the cooling system.
NOTE: The pressure relief on a "HOT" engine is approximate. Caution should always be taken when removing the radiator cap on a "HOT" engine. Additional A/C "ON" time may be required to relieve cooling system pressure properly.

3. Turn off the air conditioning.
4. Return the ignition key to the LOCK ("OFF") position.
5. Follow procedure for COLD engine listed above. 


Type or print the necessary information on a Recall Campaign identification label. The completed label should be attached to the vehicle's upper radiator support.


SUBARU WWP-99 Owner Notification Letter

Some owners may have also received an e-mail notification of the campaign before receiving the letter.

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This article was written by . It was last updated June 10, 2011 and first published November 20, 2010. If you have questions about the article, please click here to view the author's contact information including e-mail address, telephone number and mailing address.