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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 61 (Engine Controls [Self-Diagnostics 3.0L]) >> Diagnostic Tests >> DTC P0140 Or DTC P0160 >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.
  1. If FREEZE FRAME DATA has been recorded, go to next step. If FREEZE FRAME DATA has not been recorded, record FREEZE FRAME DATA. Go to next step.
  2. Verify Related Repair Information Availability -  Check for related Service Bulletins and/or on-line repair information availability. If any related repair information is available, perform repair or diagnosis according to available repair information. If vehicle is not repaired, go to next step. If related repair information is not available, go to next step.
  3. Verify Related Pending Code Or Stored DTCs -  Turn ignition off, then on (engine off). Verify pending code or stored DTCs using WDS or equivalent. If any other DTC is present, go to appropriate DTC trouble shooting procedure. Refer to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are present, go to next step.
  4. Identify Trigger DTC For FREEZE FRAME DATA -  If DTC P0140 or P0160 are on FREEZE FRAME DATA, go to next step. If DTC P0140 or P0160 triggered FREEZE FRAME DATA, go to appropriate DTC trouble shooting procedure for DTC that triggered FREEZE FRAME DATA. Refer to DIAGNOSTIC TROUBLE CODE DEFINITIONS .
  5. Verify Current Input Signal Status -  Warm up engine. Access O2S12 for P0140 or O2S22 for P0160 PID using WDS or equivalent. Verify PID while racing engine at least 10 times in Park (ATX) or Neutral (MTX). If PID reading is not 0.55 volt or more at least once during engine racing, go to next step. If PID reading is 0.55 volt or more at least once during engine racing, go to step  8.
  6. Inspect Installation Of Right & Left Front HO2Ss -  Check if right and left front HO2Ss are loosely installed. If right and left front HO2Ss are installed securely, go to next step. If either front HO2S is loose, tighten suspect HO2Ss securely. After repair, go to step  10.
  7. Inspect Gas Leakage From Exhaust System -  Visually check if any gas leakage is found between exhaust manifold and right and left front HO2Ss. If any gas leakage is present, replace faulty exhaust system component. After repair, go to step  10. If no exhaust leaks are present, inspect following harnesses for open or short circuit to ground, repair faulty wire or replace wire harness if necessary:
    • For DTC P0140: Right rear HO2S 4-pin harness connector terminal "A" and PCM 104-pin harness connector terminal No. 35 (White wire)
    • For DTC P0160: Left rear HO2S 4-pin harness connector terminal "A" and PCM 104-pin harness connector terminal No. 61 (Red wire)
    Repair or replace harness if necessary. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If all items are okay, replace faulty HO2S. After repair, go to step  10.
    8. WARNING: Removing radiator cap when radiator is hot is dangerous. Scalding coolant and steam may shoot out and cause serious injury. When removing radiator cap, wrap a thick cloth around and turn it slowly.
    NOTE: If there are any small bubbles which make engine coolant White at filler opening, air is getting in from poor sealing at head gasket or other areas between combustion chamber and engine coolant passage. Large bubbles are normal since they are remaining air coming out from engine coolant passage.
  8. Inspect Sealing Of Engine Coolant Passage -  Remove radiator cap. Perform procedure to bleed air from engine coolant, then run engine at idle. If there are any small bubbles which make engine coolant White at filler opening, repair or replace faulty parts. After repair, go to step  10. If small bubbles are not present, go to next step.
  9. Inspect Engine Compression -  Inspect engine compression. Refer to MECHANICAL INSPECTION in BASIC DIAGNOSTIC PROCEDURES article. If engine compression is okay, go to next step. If engine compression is not okay, perform engine overhaul for repairs. After repair, go to next step.
  10. Verify Trouble Shooting Of DTC P0140 Or P0160 Is Completed -  Make sure to reconnect all disconnected connectors. Turn ignition on, engine off. Clear DTC from memory using WDS or equivalent. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine. Access ECT and RPM PIDs using WDS or equivalent. Make sure that ECT PID is more than 158°F (70°C). Increase engine speed to 1500 RPM or more for 42 seconds or more. If PENDING CODE of same DTC is not present, go to next step. If PENDING CODE of same DTC is present, replace PCM. For PCM removal and installation, see POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article. After repair, go to next step.
  11. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If any DTCs are present, go to appropriate DTC inspection. Refer to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are present, trouble shooting is complete.
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