Buick Encore: Diagnostic information and procedures

Specifications

FASTENER TIGHTENING SPECIFICATIONS

DIAGNOSTIC INFORMATION AND PROCEDURES

SYMPTOMS - ENGINE EXHAUST

• Review the exhaust system description in order to familiarize yourself with the exhaust system components and the intended function of the components. Refer to Exhaust System Description.
• All diagnostics on a vehicle should follow a logical process. Strategy Based Diagnostics is a uniform approach for repairing all systems. The diagnostic flow is the place to start when repairs are necessary and may always be used in order to resolve a system problem. For a detailed explanation, refer to Strategy Based Diagnosis .

Visual/Physical Inspection

• Inspect for aftermarket or non-OEM devices such as, but not limited to; tailpipe extensions, headers, and exhaust cutouts. Any aftermarket exhaust system devices could affect the operation and proper performance of the exhaust system.
• Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
• Inspect the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.

Intermittent

Test the vehicle under the same conditions that the customer reported in order to verify the system is operating as designed.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

• Loss of power

Refer to Restricted Exhaust

• Poor acceleration

Refer to Restricted Exhaust

• Poor fuel economy

Refer to Restricted Exhaust

• Excessive smoke diesel

Refer to Restricted Exhaust

• Exhaust hissing noise

Refer to Exhaust Leakage

• Exhaust popping noise

Refer to Exhaust Leakage

• Exhaust rattle noise

Refer to Exhaust Noise

• Loud exhaust noise

Refer to Exhaust Noise

• Exhaust buzz, groan, hum noise

Refer to Exhaust Noise

Restricted exhaust

Diagnostic Aids

WARNING: Refer to Exhaust Service Warning

For dual exhaust systems a quick check of exhaust flow will help determine which side of the exhaust system is restricted. The side that has less exhaust flow is the side that will be suspect, and diagnosis should begin there.

NOTE: This will not apply if the dual exhaust is equipped with an "H" pipe or similar configuration in which the exhaust flow would be equalized.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

4

The exhaust system has very low back pressure under normal conditions. If the exhaust system is restricted, a significant increase in the exhaust pressure is noticed on the J-35314-A Exhaust Back Pressure Gauge.

Removing the AIR check valve or HO2S sensor may set a DTC. When finishing this diagnostic table, be sure to clear all codes.

5

This step will isolate the catalytic converter from the remainder of the exhaust system.

8

Confirming that the condition has been fixed is essential. If the symptom still exists and the vehicle has a dual exhaust system, proceed to Step 2 and repeat diagnostic procedure on the opposite exhaust pipe.

Restricted Exhaust

EXHAUST LEAKAGE

Exhaust Leakage

EXHAUST NOISE

Exhaust Noise

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