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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 P0112: Intake Air Temperature Sensor Circuit Low Input >> Diagnostic Procedure
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Diagnostic Procedure

  1. Verify Related Repair Information Availability -  Turn ignition off. Connect scan tool to DLC-2. See Figure. Turn ignition on, engine off. 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. Inspect IAT Sensor Terminal -  Turn ignition off. Disconnect IAT sensor harness connector. See Figure. Check IAT sensor connector terminals for damaged, bent, 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.
  3. Determine If IAT Sensor Malfunction Or Harness Malfunction -  Measure resistance between IAT sensor connector terminals. Resistance reading should be 2200-2690 ohms at 68°F (20°C). If resistance reading is as specified, go to next step. If resistance reading is not as specified, replace IAT sensor. After repair, go to step  6.
  4. Inspect IAT Signal Circuit For Short To GND -  Disconnect PCM 31-pin harness connector. See Figure. Check for continuity between ground and IAT sensor harness connector terminal "B" (Pink/Blue wire). If continuity is not present, go to next step. If continuity is present, repair short circuit to ground inPink/Blue wire between IAT sensor harness connector terminal "B" and PCM 31-pin harness connector terminal "4N". See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  6.
  5. Inspect IAT Circuits For Short Each Other -  Check for continuity between IAT sensor harness connector terminals "A" (Black/Red wire) and "B" (Pink/Blue wire). If continuity is not present, go to next step. If continuity is present, repair short between IAT sensor circuits (Black/Red and Pink/Blue wires). After repair, go to next step.
  6. Verify Troubleshooting Of DTC P0112 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 let idle until normal operating temperature is reached. Monitor for DTCs. If same DTC is not present, go to next step. If same DTC P0112 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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