Subaru Ascent 2018-2026 Owner's Manual: CHECK ENGINE warning light/Malfunction indicator light

CAUTION

If the CHECK ENGINE warning light in your Subaru Ascent turns on while driving, it is essential to have the vehicle inspected and repaired by an authorized SUBARU dealer as soon as possible. Continuing to operate the Subaru Ascent without addressing potential emission control system issues may lead to severe damage that might not be covered under the vehicle warranty.

If this indicator in the Subaru Ascent illuminates steadily or begins blinking while the engine is running, it signals that a malfunction or potential issue has been detected within the emission control system.

If the light illuminates steadily

If the CHECK ENGINE light in your Subaru Ascent remains continuously illuminated during driving or does not turn off after the engine has started, this indicates that the system has identified a fault in the emission control components.

In this situation, it is strongly recommended to have your Subaru Ascent checked promptly by a qualified SUBARU technician.

NOTE

This warning light in the Subaru Ascent may also activate if the fuel filler cap is not properly tightened until it clicks securely into place.

If you have recently refueled your Subaru Ascent, a loose or improperly sealed fuel cap may be the cause of the warning light activation.

Remove the fuel cap and reinstall it carefully, ensuring it is tightened until a clicking sound is heard. Also, verify that no debris or obstruction is preventing a proper seal. Keep in mind that the CHECK ENGINE warning light in the Subaru Ascent may not turn off immediately and may require several driving cycles to reset. If the light remains on, contact your SUBARU dealer without delay.

If the light is blinking

If the CHECK ENGINE warning light in the Subaru Ascent flashes while driving, this indicates a possible engine misfire condition that could damage the emission control system.

To minimize the risk of serious damage, take the following actions immediately.

• Reduce the driving speed of your Subaru Ascent.
• Avoid rapid or aggressive acceleration.
• Refrain from driving on steep inclines if possible.
• Decrease vehicle load by removing excess cargo if feasible.
• Stop towing a trailer as soon as it is safe to do so.

The blinking CHECK ENGINE light in the Subaru Ascent may eventually stop flashing and remain steadily illuminated after several driving cycles. Regardless, you should have the vehicle inspected by an authorized SUBARU dealer as soon as possible.

Charge warning light

If this warning light appears while the Subaru Ascent engine is running, it may indicate a malfunction within the vehicle’s charging system.

If the light stays on during operation or does not turn off after engine startup, stop the engine at the earliest safe opportunity and inspect the drive belt. If the belt is loose, damaged, or appears intact but the light remains on, contact your nearest SUBARU dealer immediately for assistance.

Oil pressure warning light

If this indicator illuminates while the Subaru Ascent engine is running, it suggests that the engine oil pressure is critically low and the lubrication system may not be functioning correctly.

If this occurs while driving or if the light does not turn off after starting the engine, safely stop the vehicle as soon as possible and contact an authorized SUBARU dealer for immediate inspection.

CAUTION

Never continue driving the Subaru Ascent with the oil pressure warning light illuminated.

Doing so can lead to severe engine damage and costly repairs.

Engine low oil level warning light

This warning light in the Subaru Ascent activates when the engine oil level drops to the minimum allowable limit, indicating that immediate attention is required to maintain proper engine performance and longevity.

Additional note: Monitoring warning indicators such as the CHECK ENGINE light in your Subaru Ascent helps ensure early detection of potential issues, improving reliability, reducing repair costs, and enhancing overall driving safety.

If the engine low oil level warning light appears in your Subaru Ascent, it is important to check the engine oil level immediately on a flat, level surface to ensure accurate measurement. If the oil level is found to be below the recommended range, refill the engine with the appropriate type of oil as specified in the Subaru Ascent maintenance guidelines. Refer to the "Engine oil" section for correct specifications. After adding or replacing oil, allow the engine to warm up fully, then switch it off on a level surface. Wait at least one minute before restarting the engine to allow the system to stabilize and correctly detect the oil level.

Once the Subaru Ascent engine is restarted, verify that the warning light has turned off. If the warning indicator remains illuminated even after refilling the oil, or if it activates despite the oil level being within the correct range, the vehicle should be inspected by an authorized SUBARU dealer without delay.

NOTE

• The Subaru Ascent system detects engine oil level immediately after the ignition switch is turned to the "OFF" position. If the oil level is below the minimum threshold when the ignition is switched back to "ON", the engine low oil level warning light will illuminate.
• When the Subaru Ascent is parked on a steep incline, the warning light may not activate even if the oil level is low, in order to prevent inaccurate readings caused by uneven oil distribution.

Windshield washer fluid warning light

This indicator in the Subaru Ascent illuminates when the windshield washer fluid level drops to the minimum threshold (approximately 0.6 US qt / 0.6 liters / 0.5 Imp qt), signaling that the reservoir should be refilled to maintain proper windshield cleaning performance.

AT OIL TEMP warning light

If this warning light appears while the Subaru Ascent engine is running, it may indicate that the automatic transmission fluid temperature has risen above safe operating limits.

If the light comes on during driving, safely pull over to a secure location and allow the engine to idle until the warning light turns off, indicating that the transmission fluid has cooled down to a normal range.

Transmission control system warning

If the "AT OIL TEMP" warning light in the Subaru Ascent flashes immediately after starting the engine, it may indicate a malfunction in the transmission control system. In such a case, contact your nearest SUBARU dealer promptly for professional servicing.

Rear differential oil temperature warning light

CAUTION

If the R.DIFF TEMP warning light in your Subaru Ascent illuminates, reduce speed immediately and stop the vehicle at the nearest safe location. Continuing to drive under these conditions may cause serious damage to the rear differential and other drivetrain components.

If this indicator activates while the engine is running, it suggests that the rear differential oil temperature is excessively high.

When driving the Subaru Ascent, if this light turns on, reduce speed and bring the vehicle to a safe stop. Allow the vehicle to remain stationary for several minutes until the warning light turns off. Once the system has cooled, you may resume driving cautiously.

If the warning light does not turn off after sufficient cooling time, it is essential to contact an authorized SUBARU dealer for inspection and repair.

NOTE

• Incorrect tire pressure or mismatched tire sizes and brands on the Subaru Ascent can place excessive strain on the rear differential, leading to elevated oil temperatures.
• If the rear differential oil temperature rises high enough to trigger the warning light, the oil may degrade and lose its effectiveness.

  In such cases, it is highly recommended to replace the rear differential oil as soon as possible to maintain optimal drivetrain performance.

Additional note: Proper monitoring and timely response to warning lights in your Subaru Ascent ensures long-term reliability, prevents costly repairs, and enhances overall driving safety in all conditions.