Diagnostic Procedure
- Turn ignition off. Connect New Generation Star (NGS) tester or equivalent to OBD-II Data Link Connector-2 (DLC-2). See Figure. Turn ignition on. Monitor for FREEZE FRAME DATA and ensure data has been recorded. Check for service bulletins and/or other line of repair information related to this DTC. If repair information is available, perform diagnosis and repair as necessary. After repair, go to step 9. If repair information is not available, go to next step.
- Start engine. Using New Generation Star (NGS) tester or equivalent, access MAF PID. MAF PID should be on a vehicle equipped with automatic transaxle 0.30-0.41 lb/min (2.2-3.2 g/sec) and with manual transaxle 0.31-0.41 lb/min (2.3-3.2 g/sec). If MAF PID is not as specified, go to next step. If MAF PID is as specified, problem is intermittent, See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
- 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 and go to step 9.
- Leave MAF sensor harness connector disconnected, turn ignition on. Measure voltage between ground and MAF harness connector terminal "C" (White/Red wire). Voltage should be battery voltage. If voltage is as specified, go to next step. If voltage is not as specified, repair open or short circuit (in White/Red wire) between MAF sensor and main relay. For circuit identification, see MIATA in WIRING DIAGRAMS article. After repair, go to step 9.
- Turn ignition off. With MAF sensor harness connector disconnected, check for continuity between ground and MAF sensor 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 and PCM. After repair, go to step 9.
- Leave MAF sensor harness connector disconnected and 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 and go to step 9.
- With MAF sensor and PCM harness connector disconnected, check for continuity between MAF sensor harness connector terminal "B" and PCM harness connector terminal "4X" (Pink wire). If continuity is found, go to next step. If continuity is not found, repair open circuit (in Pink wire) between MAF sensor and PCM. After repair, go to step 9.
- With MAF sensor and PCM harness connector disconnected, check for continuity between following circuits:
- Ground and MAF sensor harness connector terminal "B" (Pink wire).
- MAF sensor harness connector terminal "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 wires (Pink and Black/Blue wires) repair as necessary. After repair, go to next step.
- Return vehicle to original condition. Using NGS tester or equivalent, clear DTCs from PCM memory. Start engine and access MAF PID. MAF PID should be on a vehicle equipped with automatic transaxle 0.30-0.41 lb/min (2.2-3.2 g/sec) and with manual transaxle 0.31-0.41 lb/min (2.3-3.2 g/sec). Monitor for DTCs. 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. If any other DTC is present, follow appropriate DTC diagnostic procedure.