Troubleshooting Diagnostic Procedure

WARNING: This page is about a different car, the 2016 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.

Intention of troubleshooting procedure

Step 1-4
- Perform an inspection of the HO2S signal line-related parts.
Step 5-6
- Verify the condition of the HO2S installation and perform a unit inspection.
Step 7
- Perform an exhaust system parts inspection.
Step 8
- Perform an inspection of the engine compression.
Step 9
- Perform an inspection of the HO2S heater.
Step 10-11
- Verify that the primary malfunction is resolved and there are no other malfunctions.

STEP	INSPECTION	RESULTS	ACTION
1	PURPOSE: INSPECT HO2S CONNECTOR CONDITION Switch the ignition off. Disconnect the HO2S connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Is there any malfunction?	Yes	Repair or replace the connector and/or terminals, then go to Step 10.
1		No	Go to the next step.
2	PURPOSE: INSPECT PCM CONNECTOR CONDITION Disconnect the PCM connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion). Is there any malfunction?	Yes	Repair or replace the connector and/or terminals, then go to Step 10.
2		No	Go to the next step.
3	PURPOSE: INSPECT HO2S SIGNAL CIRCUIT FOR SHORT TO GROUND Verify that the HO2S and PCM connectors are disconnected. Inspect for continuity between HO2S terminal A (wiring harness-side) and body ground. Is there continuity?	Yes	Refer to the wiring diagram and verify whether or not there is a common connector between HO2S terminal A and PCM terminal 2AI. If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to ground. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has a short to ground. Go to Step 10.
3		No	Go to the next step.
4	PURPOSE: INSPECT HO2S CIRCUIT FOR OPEN CIRCUIT Verify that the HO2S and PCM connectors are disconnected. Inspect for continuity between HO2S terminal A (wiring harness-side) and PCM terminal 2AI (wiring harness-side). Is there continuity?	Yes	Go to the next step.
4		No	Refer to the wiring diagram and verify whether or not there is a common connector between HO2S terminal A and PCM terminal 2AI. If there is a common connector: Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit. Repair or replace the malfunctioning part. If there is no common connector: Repair or replace the wiring harness which has an open circuit. Go to Step 10.
5	PURPOSE: INSPECT INSTALLATION OF HO2S Verify the installation condition of the HO2S (installation angle, tightening torque value). (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Is the HO2S installed securely?	Yes	Go to the next step.
5		No	Retighten the HO2S, then go to Step 10. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
6	PURPOSE: DETERMINE INTEGRITY OF HO2S Reconnect all disconnected connectors. Inspect the HO2S. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Is there any malfunction?	Yes	Replace the HO2S, then go to Step 10. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
6		No	Go to the next step.
7	PURPOSE: VERIFY IF MALFUNCTION RELATED TO EMISSION SYSTEM AFFECTS HO2S SIGNAL Verify the exhaust gas leakage from the exhaust system. (between A/F sensor and HO2S) Is there any malfunction?	Yes	Repair or replace the malfunctioning part according to the inspection results, then go to Step 10.
7		No	Go to the next step.
8	PURPOSE: VERIFY IF MALFUNCTION RELATED TO ENGINE COMPRESSION AFFECTS DIAGNOSTIC RESULTS Inspect the engine compression. (See COMPRESSION INSPECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Are compression pressures within specification? Specification: Compression [SKYACTIV-G 2.0] Standard: 885 kPa {9.02 kgf/cm ² , 128 psi} (300 rpm) Minimum: 708 kPa {7.22 kgf/cm ² , 103 psi} (300 rpm) Maximum difference between cylinders: 150 kPa {1.53 kgf/cm ² , 21.8 psi} (300 rpm) Compression [SKYACTIV-G 2.5] Standard: 954 kPa {9.73 kgf/cm ² , 138 psi} (300 rpm) Minimum: 763 kPa {7.78 kgf/cm ² , 111 psi} (300 rpm) Maximum difference between cylinders: 161 kPa {1.64 kgf/cm ² , 23.4 psi} (300 rpm) NOTE: Because the SKYACTIV-G 2.0 and SKYACTIV-G 2.5 retards the intake valve closing timing, compression pressure is low.	Yes	Go to the next step.
8		No	Replace or overhaul the engine, then go to Step 10.
9	PURPOSE: DETERMINE INTEGRITY OF HO2S HEATER Inspect the HO2S heater. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Is there any malfunction?	Yes	Replace the HO2S, then go to the next step. (See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
9		No	Go to the next step.
10	PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION Always reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. (See CLEARING DTC [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Implement the repeatability verification procedure. (See REPEATABILITY VERIFICATION PROCEDURE .) Perform the Pending Trouble Code Access Procedure. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Is the PENDING CODE for this DTC present?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .) Go to the next step.
10		No	Go to the next step.
11	PURPOSE: VERIFY IF THERE IS ANY OTHER MALFUNCTION Is any other DTC or pending code stored?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
11		No	DTC troubleshooting completed.