Customer Concern: The Check Engine Light (CEL) is on. Trouble code P1259.
Tests/Procedures: 1. Locate the Variable Timing/Lift Control (VTEC) pressure switch on the end of the cylinder head by the distributor.
2. The VTEC oil switch is normally closed and grounds the reference voltage from the Engine Control Module (ECM) on the Blue/Black (BLU/BLK) wire.
3. At approximately 4,000 RPM and when driving the vehicle, the VTEC system should turn on. To turn the system on, the ECM energizes the VTEC solenoid valve and it allows oil pressure into the intake valve rocker arms; the oil pressure opens the VTEC oil pressure switch, so the ECM can verify that VTEC did turn on correctly.
4. The code will set below 4,000 RPM if the reference voltage is not grounded. The code will set above 4,000 RPM if the VTEC oil switch does not open.
5. If the code sets at 4,000 RPM or higher, the problem can be a low oil level or pressure or a malfunction in the VTEC assembly.
Tech Tips: When the P1259 code sets at 4,000 RPM or higher, always verify that the engine oil level is full.
Also, if there is an oil pressure or volume problem, always verify that the oil pan is not pushed up and too close to the oil pickup tube, causing an oil volume problem. Be very careful when supporting the engine with the oil pan.
This is the definition of the code P1259.
P1259 VTEC System Malfunction (Bank 1)Possible Causes Setting Conditions
•VTEC solenoid connector is damaged (check pins for damage, and moisture)
•VTEC solenoid has failed
•VTEC switch signal circuit is open or shorted to ground
•VTEC switch has failed
•PCM has failed
Engine running in Closed Loop; then accelerated in 1st gear to more than 6,000 rpm for 2 seconds, and the PCM detected a problem in the Bank 1 VTEC solenoid or its switch.
This code sets in 1 Trip(s).
This code will turn on the MIL (Malfunction Indicator Lamp)