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Home >> Mazda >> 2021 >> CX-5 Sport, FWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 22 (On-Board Diagnostic - Engine Control (VIN Y) (1 Of 3)) >> DTC P0140-00: Ho2S Circuit No Activity Detected >> Troubleshooting Diagnostic Procedure >> Intention of troubleshooting procedure

Intention of troubleshooting procedure

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

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.
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.
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.
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.
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
Yes Go to the next step.
No Retighten the HO2S, then go to Step 10.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [VIN Y] .)
6 PURPOSE: DETERMINE INTEGRITY OF HO2S
Yes Replace the HO2S, then go to Step 10.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [VIN Y] .)
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.
No Go to the next step.
8 PURPOSE: VERIFY IF MALFUNCTION RELATED TO ENGINE COMPRESSION AFFECTS DIAGNOSTIC RESULTS
Yes Go to the next step.
No Replace or overhaul the engine, then go to Step 10.
9 PURPOSE: DETERMINE INTEGRITY OF HO2S HEATER
Yes Replace the HO2S, then go to the next step.
(See HEATED OXYGEN SENSOR (HO2S) REMOVAL/INSTALLATION [VIN Y] .)
No Go to the next step.
10 PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION
Yes Repeat the inspection from Step 1.

Go to the next step.
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 .)
No DTC troubleshooting completed.