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DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSMAZDA20086 S SPORT, 4D HATCHBACK, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 17 (ON-BOARD DIAGNOSTIC (ENGINE CONTROL SYSTEM L3) (2 OF 5))DTC P0133 [L3]DIAGNOSTIC PROCEDURE

2008 Mazda 6 s Sport, 4D Hatchback, Standard

Diagnostic Procedure

2008 Mazda 6 s Sport, 4D Hatchback, StandardSECTION Diagnostic Procedure

WARNING: This page is about a different variant/trim than selected.

DTC P0133 [L3] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (HO2S related) been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS oh the repair order, then go to the next step.
2	VERIFY RELATED SERVICE INFORMATION AVAILABILITY Verify related Service Information availability. Is any related Service Information available?	Yes	Perform repair or diagnosis according to the available Service Information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	VERIFY RELATED PENDING AND STORED DTC Turn the ignition switch off, then to the ON position (Engine off). Verify the pending or stored DTCs using the M-MDS or equivalent. Is DTC P0443 also present?	Yes	Go to DTC P0443 troubleshooting procedures, then go to Step 13.
3		No	Go to the next step.
4	IDENTIFY TRIGGER, DTC FOR FREEZE FRAME DATA Is DTC P0133 on FREEZE FRAME DATA?	Yes	Go to the next step.
4		No	Go to troubleshooting procedures for DTC on FREEZE FRAME DATA. (See DTC TABLE [L3] ).
5	INSPECT INSTALLATION OF FRONT HO2S Inspect if the front HO2S is loosely installed. Is the front HO2S installed securely?	Yes	Go to the next step.
5		No	Retighten the front HO2S, then go to Step 10.
6	INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM Visually inspect if there is any gas leakage is found between the exhaust manifold and front HO2S. Is there gas leakage?	Yes	Repair or replace the malfunctioning exhaust part, then go to Step 10.
6		No	Go to the next step.
7	INSPECT FRONT HO2S Inspect the front HO2S. (See.) Is there any malfunction?	Yes	Replace the front HO2S, then go to step 10. (See.)
7		No	Go to the next step.
8	INSPECT FUEL LINE PRESSURE Turn the ignition switch off. Inspect the fuel line pressure while the engine running. (See FUEL LINE PRESSURE INSPECTION [L3, AJ] ). Is the fuel line pressure normal?	Yes	Go to the next step.
8		No	Repair or replace any malfunctioning exhaust part, then go to step 10.
9	INSPECT SEALING OF ENGINE COOLANT PASSAGE Perform the "ENGINE COOLANT LEAKAGE INSPECTION". (See ENGINE COOLANT LEAKAGE INSPECTION [L3, AJ] ). Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Then go to the next step.
9		No	Go to the next step.
10	VERIFY TROUBLESHOOTING OF DTC P0133 COMPLETED Make sure to reconnect all disconnected connectors. Turn the ignition switch to the ON position. (Engine off) Clear the DTC from the memory using the M-MDS or equivalent. Perform the HO2S heater, HO2S, and TWC Repair Verification Drive Mode. (See OBD-II DRIVE MODE [L3] ). Is the PENDING CODE for this DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L3] ).
10		No	Go to the next step.
11	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE [L3] ). Are any DTC present?	Yes	Go to the applicable DTC troubleshooting. (See DTC TABLE [L3] ).
11		No	Troubleshooting completed.

DTC P0133 [L3] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAVE BEEN RECORDED Have FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS (HO2S related) been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA and DIAGNOSTIC MONITORING TEST RESULTS on the repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Information availability. Is any related Service Information available?	Yes	Perform repair or diagnosis according to the available Service information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	VERIFY RELATED PENDING AND STORED DTC Turn the ignition switch off, then to the ON position (Engine off). Verify the pending or stored DTCs using the M-MDS or equivalent. Is the DTC P0443 also present?	Yes	Go to DTC P0443 troubleshooting procedures, then go to Step 13.
3		No	Go to the next step.
4	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA Is the DTC P0133 on FREEZE FRAME DATA?	Yes	Go to the next step.
4		No	Go to troubleshooting procedures for DTC on FREEZE FRAME DATA. (See DTC TABLE [L3] ).
5	INSPECT INSTALLATION OF FRONT HO2S Inspect if the front HO2S is loosely installed. Is the front HO2S installed securely?	Yes	Go to the next step.
5		No	Retighten the front HO2S, then go to Step 10.
6	INSPECT GAS LEAKAGE FROM EXHAUST SYSTEM Visually inspect if there is any gas leakage is found between the exhaust manifold and front HO2S. Is there gas leakage?	Yes	Repair or replace the malfunctioning exhaust part, then go to Step 10.
6		No	Go to the next step.
7	INSPECT FRONT HO2S Inspect the front HO2S. (See.) Is there any malfunction?	Yes	Replace the front HO2S, then go to step 10. (See.)
7		No	Go to the next step.
8	INSPECT FUEL LINE PRESSURE Turn the ignition switch off. Inspect the fuel line pressure while the engine running. (See FUEL LINE PRESSURE INSPECTION [L3, AJ] ). Is the fuel line pressure normal?	Yes	Go to the next step.
8		No	Repair or replace any malfunctioning exhaust part, then go to step 10.
9	INSPECT SEALING OF ENGINE COOLANT PASSAGE Perform the "ENGINE COOLANT LEAKAGE INSPECTION". (See ENGINE COOLANT LEAKAGE INSPECTION [L3, AJ] ). Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results. Then go to the next step.
9		No	Go to the next step.
10	VERIFY TROUBLESHOOTING OF DTC P0133 COMPLETED Make sure to reconnect all disconnected connectors. Turn the ignition switch to the ON position. (Engine off) Clear the DTC from the memory using the M-MDS or equivalent. Perform the HO2S heater, HO2S, and TWC Repair Verification Drive Mode. (See OBD-II DRIVE MODE [L3] ). Is the PENDING CODE for this DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [L3] ).
10		No	Go to the next step.
11	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE [L3] ). Are any DTC present?	Yes	Go to the applicable DTC troubleshooting. (See DTC TABLE [L3] ).
11		No	Troubleshooting completed.

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.