## DTC Troubleshooting: P1259 (22-4)

DTC P1259 (22-4): | VTEC System Malfunction

Special Tools Required
Oil pressure gauge attachment ( 07NAJ-P070100)

Low pressure gauge ( 07406-0070001)

1. | Reset the ECM/PCM.

2. | Check the engine oil level, and refill if necessary. Check for external damage to the oil pan.

3. | Start the engine. Hold the engine at 3,000 rpm (min-1) without load (in Park or neutral) until the radiator fan comes on.

4. | Road test the vehicle: Accelerate in M/T: 2nd gear (CVT: D position) to an engine speed over 4,000 rpm (min-1). Hold that engine speed for at least 2 seconds. If DTC P1259 is not repeated during the first road test, repeat this test two more times. Is DTC P1259 indicated? YES - Go to 5. NO - Intermittent failure, system is OK at this time. Check the oil consumption if oil was added in 2. Check for poor connections or loose terminals at the VTEC solenoid valve and at the ECM/PCM.n

5. | Turn the ignition switch OFF.

6. | Disconnect the VTEC oil pressure switch 2P connector.

7. | Check the VTEC oil pressure switch for continuity between VTEC oil pressure switch 2P connector terminals No. 1 and No. 2. Is there continuity? YES - Go to 8. NO - Replace the VTEC oil pressure switch.n

8. | Turn the ignition switch ON (II).

9. | Measure voltage between VTEC oil pressure switch 2P connector terminal No. 1 and body ground. Is there battery voltage? YES - Go to 14. NO - Go to 10.

10. | Measure voltage between ECM/PCM connector terminal B9 and body ground. Is there battery voltage? YES - Repair open in the wire between the VTEC oil pressure switch and the ECM/PCM (B9).n NO - Go to 11.

11. | Turn the ignition switch OFF.

12. | Disconnect ECM/PCM connector B (24P).

13. | Check for continuity between ECM/PCM connector terminal B9 and body ground. Is there continuity? YES - Repair short in the wire between the VTEC oil pressure switch and the ECM/PCM (B9).n NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/ PCM.n

14. | Measure voltage between VTEC oil pressure switch 2P connector terminals No. 1 and No. 2. Is there battery voltage? YES - Go to 15. NO - Repair open in the wire between the VTEC oil pressure switch and G101.n

15. | Turn the ignition switch OFF.

16. | Disconnect the VTEC solenoid valve 2P connector.

17. | Check for resistance between VTEC solenoid valve 2P connector terminals No. 1 and No. 2. Is there 14-30 W? YES - Go to 18. NO - Replace the VTEC solenoid valve.n

18. | Remove the VTEC oil pressure switch (A) and install the special tools as shown, then reinstall the VTEC oil pressure switch.

19. | Reconnect the VTEC solenoid valve 2P connector and VTEC oil pressure switch 2P connector.

20. | Connect a tachometer, a scan tool, or the HDS.

21. | Start the engine. Hold the engine at 3,000 rpm (min-1) without load (in Park or neutral) until the radiator fan comes on.

22. | Check the oil pressure at engine speeds of 1,000 and 2,000 rpm (min-1). Keep the measuring time as short as possible (less than 1 minute) because the engine is running with no load. Is the oil pressure below 49 kPa (0.5 kgf/cm2, 7 psi)? YES - Go to 23. NO - Inspect the VTEC solenoid valve.n

23. | Turn the ignition switch OFF.

24. | Disconnect the VTEC solenoid valve 2P connector.

25. | Attach the battery positive terminal to VTEC solenoid valve 2P connector terminal No. 2.

26. | Start the engine, then connect the battery negative terminal to VTEC solenoid valve 2P connector terminal No. 1, and check the oil pressure at an engine speed of 3,000 rpm (min-1). Is the oil pressure above 390 kPa (4.0 kgf/cm2, 57 psi)? YES - Go to 27. NO - Inspect the VTEC solenoid valve.n

27. | With the battery terminals still connected to the VTEC solenoid valve connector, measure voltage between ECM/PCM connector terminal B9 and body ground. Is there battery voltage above 4,000 rpm (min-1)? YES - Go to 28. NO - Replace the VTEC oil pressure switch.n

28. | Turn the ignition switch OFF.

29. | Disconnect the battery terminals from the VTEC solenoid valve terminal connector.

30. | Disconnect ECM/PCM connector B (24P).

31. | Check for continuity between ECM/PCM connector terminal B15 and body ground. Is there continuity? YES - Repair short in the wire between the VTEC solenoid valve and the ECM/PCM (B15).n NO - Go to 32.

32. | Connect the VTEC solenoid valve 2P connector terminal No. 1 and body ground with a jumper wire.

33. | Check for continuity between ECM/PCM connector terminal B15 and body ground. Is there continuity? YES - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/ PCM.n NO - Repair open in the wire between the VTEC solenoid valve and the ECM/PCM (B15).n