The Magnuson-Moss Act
The Magnuson-Moss Act does not require any business to provide a written warranty, but if a business offers a written warranty on a consumer product, it must comply with the Act. The Act does not apply to oral warranties. Only written warranties are covered. The Act applies only to goods, and does not apply to warranties on services. However, if a warranty covers both parts for a repair and workmanship in making the repair, the Act can apply. The Act covers only warranties on consumer products, and does not apply to warranties on products sold for resale or for commercial purposes.  This means that only warranties on tangible property normally used for personal, family, or household purposes are covered, including some property attached to or installed on real property. While oral warranties are important, only written warranties on consumer products are covered by the Magnuson-Moss Warranty Act. See Title 15 U.S.Code Section 45, Magnuson-Moss Warranty - Federal Trade Commission Improvement Act

Implied Warranties
Implied warranties are unspoken, unwritten promises, created by state law, from a seller or merchant, to buyers. There are two basic types of implied warranties in consumer product transactions. They are the implied warranty of merchantability and the implied warranty of fitness for a particular purpose.

The implied warranty of merchantability is a basic promise that goods sold will do what they are supposed to do and that there is nothing significantly wrong with them. It is an implied promise that the goods are fit to be sold. The law holds that merchants make this promise automatically every time they sell a product they are in business to sell.

The implied warranty of fitness for a particular purpose is a promise that the law requires a seller to make when a customer relies on merchant's advice that a product can be used for a specific purpose. For example, a  merchant may be asked by a customer for a product to perform a specialized and specific task. If the merchant recommends a particular model, and the customer buys that model on the strength of the recommendation, the law in many states says that the merchant has made a warranty of fitness for a particular purpose. If the product recommended proves unable to perform this specific task, the warranty of fitness for a particular purpose is breached.

Implied warranties are promises about the condition of products at the time they are sold, but they do not assure that a product will last for any specific length of time. The normal durability of products may be one aspect of merchantability or its fitness for a particular purpose, however. Implied warranties do not cover items such as abuse, misuse, ordinary wear, failure to follow directions, or improper maintenance.

Requirements of the Magnuson-Moss Act 
In passing the Magnuson-Moss Warranty Act, Congress specified a number of requirements that warrantors must meet, and directed the Federal Trade Commission to adopt rules to cover other requirements. The Federal Trade Commission (FTC) adopted three Rules under the Act, the Rule on Disclosure of Written Consumer Product Warranty Terms and Conditions (the Disclosure Rule), the Rule on Pre-Sale Availability of Written Warranty Terms (the Pre-Sale Availability Rule), and the Rule on Informal Dispute Settlement Procedures (the Dispute Resolution Rule). In addition, the FTC has issued an interpretive rule that clarifies certain terms and explains some of the provisions of the Act.

The Act and the Rules establish three basic requirements that may apply as a warrantor or a seller.

1. A warrantor must designate, or title, a written warranty as either "full" or "limited"
2. A warrantor must state certain specified information about the coverage of the warranty in a single, clear, and easy-to read document.
3. A warrantor or a seller must ensure that warranties are available where warranted consumer products are sold so that consumers can read them before buying.

The titling requirement, established by the Act, applies to all written warranties on consumer products costing more than $10. However, the disclosure and pre-sale availability requirements, established by FTC Rules, apply to all written warranties on consumer products costing more than $15.

Disclaimer or Modification of Implied Warranties
The Act prohibits anyone who offers a written warranty from disclaiming or modifying implied warranties. This means that no matter how broad or narrow a written warranty is, customers always will receive the basic protection of the implied warranty of merchantability. There is one permissible modification of implied warranties, however. If a "limited" written warranty is offered, the law allows a  restriction on the duration of implied warranties to the duration of the limited warranty. For example, with a two-year limited warranty,  implied warranties can be limited to two years. But if a "full" written warranty is offered, the duration of implied warranties cannot be limited.

"Tie-In Sales" Provisions
Generally, tie-in sales provisions are not allowed. Such a provision would require a purchaser of the warranted product to buy an item or service from a particular company to use with the warranted product in order to be eligible to receive a remedy under the warranty. But the warranty need not cover use of replacement parts, repairs, or maintenance which are inappropriate for product. A provision that excludes coverage of such things suggested by the FTC is "Improper or incorrectly performed maintenance or repair voids this warranty".

Deceptive Warranty Terms
Obviously, warranties must not contain deceptive or misleading terms. You cannot offer a warranty that appears to provide coverage but, in fact, provides none. For example, a warranty covering only "moving parts" on an electronic product that has no moving parts would be deceptive and unlawful. Similarly, a warranty that promised service that the warrantor had no intention of providing or could not provide would be deceptive and unlawful.

Additional information is available from the Federal Trade Commission, including Understanding Warranties,  Titling Written Warranties as "Full" or "Limited", and What the Magnuson-Moss Act Requires.