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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 P0103: Mass Airflow Sensor Circuit High 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  6.
  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 reading is not as specified, go to next step. If MAF PID reading 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 Figure. 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  6.
  4. Inspect MAF Signal Circuit For Short To Power Circuit -  Turn ignition on, engine off. Measure voltage between ground and MAF harness 3-pin harness connector terminal "B" (Pink wire). Voltage reading should be 0.1 volt. If voltage reading is as specified, go to next step. If voltage reading is not as specified, repair short circuit in Pink wire between MAF sensor 3-pin harness connector terminal "B" and PCM 31-pin harness connector terminal "4X". See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  6.
  5. Inspect PCM Connector For Poor Connection -  Turn ignition off. Disconnect PCM 31-pin harness connector. See Figure. 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  6.
  6. Verify Troubleshooting Of DTC P0103 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 P0103 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.
  7. 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 .
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