Hey Im New To This But I Thought Id Give It A Shot. I Have A 1999 Tl And The Check Engine Light Is On. I Had It Checked By Autozone And The Code Came Back 'p1259 V-tech System Malfunction'. The V-tech Works Fine And The Oil Level Is Fine. Could It Be That The Recommended 5w-30 Is Too Thin For A Car With 108,000 Miles?? Everything Is Working Fine No Problems So Mayve It Was A Temporary Low Oil Pressure Reading??? Any Help Would Be Great Thanks.

 

1. Locate the Variable Timing/Lift Control (VTEC) pressure switch, on the back of the cylinder block, by the oil filter.

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 4000 RPM, and when driving the vehicle, the VTEC system should turn on. To turn on the system, 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 the VTEC did turn on correctly.

4. The code will set below 4000 RPM if the reference voltage is not grounded. The code will set above 4000 RPM if the VTEC oil switch does not open.

5. If the code sets at 4000 RPM or higher, the problem can be a low oil level or pressure or a malfunction in the VTEC assembly.

 

Thanks. The Light Came On Around 2,000-2,500 Rpm, So It Sounds Like It Was A Short Or Something. I Took A Look At The Switch - Its The One With The Green Plastic Cover Right? - And It Looked Fine, No Exposed Wires Or Anything. Anyway The Light Has Gone Out Now For A Whole Day.....we'll See. If It Does Re-appear, What Can I Do To Fix It? - [reference Voltage Not Grounded] Replace? Repair? Thanks For The Help!

 

If it comes on again you can either replace it and hope thats the problem, inspect all the wiring and see if its been chewed thru bu a rodent or bring it in. Stuff like that can be hard to track down due to the nature of it.