Subaru Ascent 2018-2026 Owner's Manual: State emission testing (U.S. only)

WARNING

When performing emission testing on a Subaru Ascent equipped with All-Wheel Drive (AWD), only a four-wheel dynamometer must be used.

Under no circumstances should the Subaru Ascent be tested on a two-wheel dynamometer. Doing so can cause uncontrolled wheel rotation, leading to dangerous vehicle movement and a high risk of accidents or serious injury to nearby personnel.

CAUTION

• Before any state inspection, always inform the inspection facility that your Subaru Ascent is an AWD vehicle and must not be placed on a two-wheel dynamometer.

  Failure to follow this requirement may result in severe transmission damage and drivetrain failure.

• Any damage caused by improper testing procedures is not covered under the SUBARU Limited Warranty and becomes the responsibility of the inspection facility or its contractors.

In the United States, including California and many other states, emission inspection programs are in place to ensure that vehicles such as the Subaru Ascent meet environmental standards. If the vehicle does not pass the emission test, registration renewal may be denied depending on local regulations.

The Subaru Ascent is equipped with an advanced onboard computer system that continuously monitors the performance of the engine and emission control components. During inspection, certified technicians evaluate the On-Board Diagnostics II (OBDII) system, which is designed to detect issues that may increase emissions beyond allowable limits.

OBDII inspections apply to all passenger vehicles manufactured from the 1996 model year onward, including the Subaru Ascent, and are widely implemented across more than 30 states and the District of Columbia.

• The inspection process includes verifying proper operation of the "CHECK ENGINE" warning light and scanning the Subaru Ascent diagnostic system using specialized electronic equipment.
• The Subaru Ascent passes the inspection if the warning light functions correctly, no diagnostic trouble codes are stored, and all OBDII readiness monitors are completed.
• The vehicle fails the inspection if the "CHECK ENGINE" light is illuminated, malfunctioning, or if any diagnostic trouble codes are detected in the system.
• The inspection may be marked as incomplete (neither pass nor fail) if more than one readiness monitor is in a "NOT READY" state. This condition often occurs if the battery has recently been disconnected or replaced in the Subaru Ascent.

  In such cases, the driver should operate the vehicle for several days under normal driving conditions to allow the system to reset before returning for re-inspection.

• If the Subaru Ascent does not pass or is rejected during testing, it is recommended to contact an authorized SUBARU dealer for professional diagnostics and repair.

Some states still utilize dynamometers as part of their emission testing procedures. A dynamometer simulates road conditions by allowing the wheels of the Subaru Ascent to rotate while the vehicle remains stationary.

Before the Subaru Ascent is positioned on any dynamometer, it is essential to inform the technician that the vehicle is AWD and must not be tested using a two-wheel system.

Failure to follow this instruction can result in extensive damage to the drivetrain and transmission components.

The U.S. Environmental Protection Agency (EPA), along with states that rely on two-wheel dynamometer systems, has officially exempted Subaru Ascent AWD vehicles from this type of testing. However, in facilities equipped with four-wheel dynamometers, testing can be conducted safely when performed correctly.

At no time should the rear wheels of the Subaru Ascent be lifted off the ground or the driveshaft disconnected in an attempt to bypass AWD functionality during emission testing. Such practices are unsafe and can lead to mechanical failure.

Proper emission testing of the Subaru Ascent must always involve a full AWD dynamometer setup, where all four wheels are engaged and under load conditions.

The Subaru Ascent emission control and diagnostic systems are engineered to meet strict environmental standards, but correct testing procedures are essential to maintain vehicle integrity and ensure accurate inspection results.