Definition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

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Go to

A Powertrain On Board Diagnostic (OBD) System Check2.4L

A Powertrain On Board Diagnostic (OBD) System Check2.2L

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found, correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

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Go to Step 3

Was visual/physical check performed?

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Go to

Important Preliminary Checks2.4L

Important Preliminary Checks2.2L

If the scan tool readings are normal, Refer to Engine Scan Tool Data List and there are no engine mechanical faults, fill fuel tank with a known quality gasoline that has a minimum octane reading of 92 and re-evaluate vehicle performance.

Is the detonation present?

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Go to Step 14

1. Check for obvious overheating problems:

•	Low engine coolant.

•	Restricted air flow to radiator, or restricted water flow through radiator.

•	Inoperative electric cooling fan circuit(s), refer to Electric Cooling Fan Diagnosis 2.4L or Electric Cooling Fan Diagnosis 2.2L.

•	Correct coolant solution should be a 50/50 mix of approved antifreeze/coolant and water. Refer to Engine Cooling.

2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 6

1. Check the fuel pressure. Refer to Fuel System Diagnosis 2.4L, Fuel System Diagnosis 2.2L.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 7

1. Check the items that can cause an engine to run lean. For a lean condition, refer to DTC P0171 Fuel Trim System Lean 2.4L or DTC P0171 Fuel Trim System Lean 2.2L for diagnosis.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 8

1. Check the spark plugs for proper heat range. Refer to Ignition System 6D4 .
2. If incorrect spark plugs are installed, replace spark plugs as necessary.

Did any spark plugs require replacement?

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Go to Step 9

1. Remove excessive carbon buildup with a top engine cleaner. Refer to instructions on top engine cleaner can.
2. Re-evaluate vehicle performance.

Is the detonation still present?

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Go to Step 14

1. Check the Knock Sensor (KS) system for proper operation. Refer to Knock Sensor (KS) System Diagnosis 2.4L or Knock Sensor (KS) System Diagnosis 2.2L for diagnosis.
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 11

1. Check for an engine mechanical problem. Perform a cylinder compression check (refer to Engine section).
2. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 12

1. Check the intake valves for valve deposits.
2. If deposits are found, remove as necessary.

Were deposits found on the intake valves?

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Go to Step 13

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no malfunctions have been found, review/inspect the following items:

•	Visual/physical inspection.

•	Scan tool data.

•	All electrical connections within a suspected circuit and/or system.

3. If a problem is found, repair as necessary.

Was a problem found?

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Go to Step 14

Check for Service Bulletins

Operate vehicle within the conditions under which the original symptom was noted.

Does the system now operate properly?

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System OK

Go to Step 2