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Home >> Mazda >> 2003 >> MX-5 Miata Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0102: Mass Airflow Sensor Circuit Low Input >> Diagnostic Procedure

Diagnostic Procedure

  1. Verify Related Repair Information Availability -  Turn ignition off. Connect scan tool to DLC-2. See Figure. Turn ignition on. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check service bulletins for repair information related to this DTC. If repair information is not available, go to next step. If repair information is available, perform diagnosis and repair as necessary. After repair, go to step  9.
  2. Verify Current Input Signal Status - Is Concern Intermittent Or Constant -  Start engine. Using scan tool, access MAF PID. MAF PID should be on a vehicle equipped with automatic transmission 0.30-0.41 lb/min (2.2-3.2 grams/sec) and with manual transmission 0.31-0.41 lb/min (2.3-3.2 grams/sec). If MAF PID is not as specified, go to next step. If MAF PID is as specified, problem is intermittent. See INTERMITTENTS in TROUBLESHOOTING - NO CODES article.
  3. Inspect MAF Sensor Connector For Poor Connection -  Turn ignition off. Disconnect MAF sensor 3-pin harness connector. See Fig 1. Check for poor connection due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are found faulty, repair or replace as necessary. After repair, go to step  9.
  4. Check Power Supply Circuit For Open -  Turn ignition on, engine off. Measure voltage between ground and MAF sensor 3-pin harness connector terminal "C" (White/Red wire). Voltage reading should be battery voltage. If voltage reading is as specified, go to next step. If voltage reading is not as specified, repair open circuit in White/Red wire between MAF sensor 3-pin harness terminal "C" and main relay. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  9.
  5. Inspect MAF Sensor GND Circuit For Open Circuit -  Turn ignition off. Check for continuity between ground and MAF sensor 3-pin harness connector terminal "A" (Black/Blue wire). If continuity is found, go to next step. If continuity is not found, repair open circuit in Black/Blue wire between MAF sensor 3-pin harness connector terminal "A" and PCM 32-pin harness connector terminal "4A". After repair, go to step  9.
  6. Inspect Poor Connection Of PCM Connector -  Disconnect PCM 31-pin harness connector. See Fig 1. Check for poor connection due to damaged, pulled-out pins, corrosion, etc. If connector terminals are okay, go to next step. If connector terminals are found faulty, repair or replace as necessary. After repair, go to step  9.
  7. Inspect MAF Sensor Signal Circuit For Open Circuit -  Check for continuity between MAF sensor 3-pin harness connector terminal "B" and PCM 31-pin harness connector terminal "4X" (Pink wire). If continuity is present, go to next step. If continuity is not present, repair open circuit in Pink wire between MAF sensor 3-pin harness connector terminal "B" and PCM 31-pin harness connector terminal "4X". After repair, go to step  9.
  8. Inspect MAF Sensor Signal Circuit For Short -  Check for continuity between following circuits:
    • Ground and MAF sensor 3-pin harness connector terminal "B" (Pink wire).
    • MAF sensor 3-pin harness connector terminals "A" (Black/Blue wire) and "B" (Pink wire).

    If continuity is not found, replace MAF sensor and go to next step. If continuity is found, repair short to ground in Pink wire or short circuit between Pink and Black/Blue wires. Repair as necessary. After repair, go to next step.

  9. Verify Troubleshooting Of DTC P0102 Completed -  Return vehicle to original condition. Using scan tool, clear DTCs from PCM memory. See CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Start engine and access MAF PID. MAF PID should be on a vehicle equipped with automatic transmission 0.30-0.41 lb/min (2.2-3.2 grams/sec) and with manual transmission 0.31-0.41 lb/min (2.3-3.2 grams/sec). Monitor for DTCs. If same DTC is not present, go to next step. If same DTC P0102 is present, replace PCM. For PCM removal and installation, see POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article. After repair, go to next step.
  10. Verify After Repair Procedure -  Using scan tool, perform After Repair Procedure. See AFTER REPAIR PROCEDURE . If no other DTCs are present, testing is complete. If any other DTC is present, follow appropriate DTC diagnostic procedure. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
Fig 1: Identifying Mass Airflow Sensor, Main Relay & Powertrain Control Module Harness Connectors & Terminals
G00140055Courtesy of MAZDA MOTORS CORP.
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