We have a 4 cyl. VTECH 2000 model Accord with an oil light on and a p1259 code. As I understand this code is set w/ low oil pressure below 4000to 6000 rpm. I assumed that these things were related. The owner has been driving this with the oil light on for some time. When I checked the oil pressure switch I found two directly over the oil filter. One on the driver and one on the passenger side. What do each one of these sensors provide?

 

This repair turned into a quick fix. Due to the fact that I am wheelchair bound, I never was able to see the underside of this engine. I had a friend install an oil pressure gauge into the oil pressure sender port over the filter. By the way the other sensor next to it was a knock sensor. The engine only produced 6 to 10 psi. (just enough to prevent the bottom end from coming apart). The oil pan was caved in right below the pick up tube almost completely starving the oil pump. We pulled the pan, replaced the pick up tube and the pan and retested. It now develops 60psi @ idle. The code did not reoccur. This engine has 410,000+ miles on it and runs beautifully. On a more technical note, the VTEC oil pressure sensor next to the control valve on the head requires a minimum oil pressure to break the ground allowing VTEC oil flow into the valve train. Does any one know what is the min. pressure required to trip the VTEC oil pressure sensor? I do know that low pressure @ this sensor will set a code P1259. All is well that ends well!!

 

im pretty sure one of those is a knock sensor, and one is oil pressure. Both are one wire. the knock is usually the sensor mounted highest on the block so it can listen in the combustion chambers.

 

Knock sensor is positioned between cylinders 2 and 3, the oil switch is parallel to the oil passages on the block, should be very easy to spot.

VTEC oil pressure switch?

 

https://honda-tech.com/forums/hybrid-engine-swaps-18/%5Bfaq%5D-%22my-vtec-doesnt-work%22-1812135/

scroll down to the OBD2 section for oil pressure testing procedures for VTEC