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DTC P1259: Variable Valve Timing & Lift Electronic Control System Malfunction

WARNING: This page is about a different car, the 2003 Acura RSX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform ECM/PCM reset procedure. See ECM/PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. Check engine oil level and top off if necessary. Check for external damage to oil pan (K20A3 engine). Start engine and run at 3000 RPM, with no load (in park or neutral), until radiator fan comes on. Road test vehicle. Accelerate in 1st gear to more than 4000 RPM and hold for at least 2 seconds. If DTC P1259 does not reset during first road test, repeat road test 2 more times. If DTC P1259 resets, go to next step. If DTC P1259 does not reset, problem is intermittent. System is functioning properly at this time. Check for poor connection(s) or loose wire(s) between Variable Valve Timing & Lift Electronic Control (VTEC) solenoid valve 2-pin harness connector and ECM/PCM 24-pin "B" harness connector. See Figure . See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. Repair as necessary.
  2. Turn ignition switch off. Disconnect VTEC oil pressure switch 2-pin harness connector. Check for continuity between VTEC oil pressure switch 2-pin connector terminals. If continuity is present, go to next step. If continuity is not present, replace VTEC oil pressure switch.
  3. Turn ignition switch on. Measure voltage between ground and VTEC oil pressure switch 2-pin harness connector terminal No. 1 (Blue/Black wire). If battery voltage is present, go to step  6 . If battery voltage is not present, go to next step.
  4. Measure voltage between ground and ECM/PCM 24-pin "B" harness connector terminal No. 9 (Blue/Black wire). If battery voltage is not present, go to next step. If battery voltage is present, repair open in Blue/Black wire between ECM/PCM 24-pin "B" harness connector terminal No. 9 and VTEC oil pressure switch 2-pin harness connector terminal No. 1.
  5. Turn ignition switch off. Disconnect ECM/PCM 24-pin "B" harness connector. Check for continuity between ground and ECM/PCM 24-pin "B" harness connector terminal No. 9 (Blue/Black wire). If continuity is present, repair short in Blue/Black wire between ECM/PCM 24-pin "B" harness connector and VTEC oil pressure switch 2-pin harness connector terminal No. 1. If continuity is not present, update ECM/PCM or substitute with known-good ECM/PCM. If symptom or indication goes away, replace original ECM/PCM.
  6. Measure voltage between VTEC oil pressure switch 2-pin harness connector terminals. If battery voltage is present, go to next step. If battery voltage is not present, repair open in Brown/Yellow wire between VTEC pressure switch 2-pin harness connector terminal No. 2 and ground terminal G101.
  7. Turn ignition switch off. Disconnect VTEC solenoid valve 2-pin harness connector. Check resistance between VTEC solenoid valve 2-pin connector terminals. If resistance reading is 14-30 ohms, go to next step. If resistance reading is not as specified, replace VTEC solenoid valve. See VTC OIL CONTROL SOLENOID VALVE (RSX) under VARIABLE VALVE TIMING & LIFT ELECTRONIC CONTROL SYSTEM in REMOVAL & INSTALLATION article.
    8. CAUTION: Keep measuring time as short as possible (less than one minute) because of engine running with no load.
    Fig 1: Testing VTEC System Oil Pressure
    G00110175Courtesy of AMERICAN HONDA MOTOR CO., INC.
  8. Remove VTEC oil pressure switch. Install Oil Pressure Hose (07ZAJ-S5A0200), A/T Pressure Hose (07406-0020201 or 07MAJ-PY4011A), A/T Pressure Adapter (07MAJ-PY40120), Pressure Gauge Adaptor (07NAJ-P07010A) and A/T Low Pressure Gauge (07406-0070300). Reinstall VTEC oil pressure switch into A/T Pressure Adapter (07MAJ-PY40120). Reconnect VTEC oil pressure switch 2-pin harness connector. See Fig 1 . Connect tachometer on scan tool. Start engine and run at 3000 RPM, with no load (in park or neutral), until radiator fan comes on. Road test vehicle. Check oil pressure at 1000 and 2000 RPM. If oil pressure is less than 7 psi (0.5 kg/cm2 ) go to next step. If oil pressure is not as specified, Inspect VTEC solenoid valve.
  9. Turn ignition switch off. Disconnect VTEC solenoid valve 2-pin harness connector. Connect fused jumper wire between positive battery terminal and VTEC solenoid valve 2-pin connector terminal No. 2. Start engine, then connect negative battery terminal to VTEC solenoid valve 2-pin connector terminal No. 1. Increase engine speed to 3000 RPM and check oil pressure. If oil pressure is 57 psi (4.0 kg/cm2 ), go to next step. If oil pressure is not as specified, Inspect VTEC solenoid valve. See VTC OIL CONTROL SOLENOID VALVE (RSX) under VARIABLE VALVE TIMING & LIFT ELECTRONIC CONTROL SYSTEM in REMOVAL & INSTALLATION article.
  10. With battery terminals still connected to VTEC solenoid valve 2-pin connector, measure voltage between ground and ECM/PCM 24-pin "B" harness connector terminal No. 9 (Blue/Black wire). If battery voltage is present at more than 4000 RPM go to next step. If voltage is not as specified, inspect VTEC oil pressure switch.
  11. Turn ignition switch off. Disconnect battery terminals from VTEC solenoid valve terminals. Disconnect ECM/PCM 24-pin "B" harness connector. Check for continuity between ground and ECM/PCM 24-pin "B" harness connector terminal No. 15 (Green/Yellow wire). If continuity is not present, go to next step. If continuity is present, repair short in Green/Yellow wire between VTEC solenoid valve 2-pin harness connector terminal No. 2 and ECM/PCM 24-pin "B" harness connector terminal No. 15.
  12. Connect fused jumper wire between ground and VTEC solenoid valve 2-pin harness connector terminal No. 2 (Green/Yellow wire). Check for continuity between ground and ECM/PCM 24-pin "B" harness connector terminal No. 15 (Green/Yellow wire). If continuity is present, update ECM/PCM or substitute with known-good ECM/PCM. If symptom or indication goes away, replace original ECM/PCM. If continuity is not present, repair open in Green/Yellow wire between VTEC solenoid valve 2-pin harness connector terminal No. 2 and ECM/PCM 24-pin "B" harness connector terminal No. 15.
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