DRTYDZL

Heys guys, new to the forum, have abit of a problem with my 2008 civic DXG. Last week check engine light came on and car would not rev past 3500rpms.
Pulled a P0522 oil pressure switch low voltage. So heres the breakdown of what Ive checked:

Unplugged connector at oil switch, measured voltage, reading was 2.5volts
Tested switch, with engine off, switch is grounded, no resistance in switch.
Unplugged harness at ECU, tested wire from ECU to to oil pressure switch connector, solid connection to ground and no short to +.
Bought and installed new switch, as old switch was leaking some oil. Did not fix problem.
With car off, evertime i try to clear the code it immediately comes back.
Have a spare ECU on hand, thinking something might have went wrong inside the ecm, swapped ecms, code is still there and cannot be cleared.

I have physically check the entire harness in the car and there is no rodent attacks or chaffing to be found anywhere.

Any insight would be greatly appreciated.

ezone

You're probably chasing the wrong item.
The code refers to the 3 wire pressure sensor in the vtec valve, not the pressure switch on the front of the block.

DRTYDZL

P2647 if Im not mistaken, is the code that relates to the vtech valve. When I unplugged the Vtech valve P2647 generated, and the scan tool identifies it as the rocker arm oil pressure switch. As well the low voltage p0522 was still present while the vtech switch was unplugged.

ezone

P2647 definition: "vtec system stuck on".
P0522 definition: "engine oil pressure sensor circuit low voltage".

Those are very different and IMO the definition of each code is pretty clear and descriptive. (the definitions above are from Hondas service information)

Can your scanner display live data, and is the EOP data shown in that list?

Do you need the colors of the three wires for the EOP sensor just to make sure you're in the correct area?

Right, because the PCM still has an issue with the voltage received or "sees" from the EOP sensor, in addition to the new code you created by (I assume) unplugging the vtec solenoid.

DRTYDZL

My scanner doesnt supply live data, by unpluggin the switch would that not interupt the voltage the ECU recieves back? Ill test voltage at the Vtech sensor, Im assuming I should see 5volts? Colors of those wires would be great too if you have them handy.

Does 2.5volts at the OP sensor seem low to you? If I understand the OP switch system, when its grounded to the block theres 0 volts and the engine thinks its run out of oil, when engine starts oil pressure builds and removes ground and voltage is created in the circuit. Wiring diagram says there should be 12vs coming from the ECU. If the ECU is only seeing 2.5vs could that maybe be triggering the code.

From reasearch Ive done so far, codes P0522 low voltage and P0523 highvoltage all seem to point at an oil pressure sensors in other vehicle applications. Maybe Hondas different though.

Thanks for your insight on the issue.

ezone

Pic stolen from Majestic Honda online parts catalog.
EOP sensor is #12
It's not a switch, it's a sensor.
The output from sensor to PCM will vary depending on the oil pressure, and it also changes depending on whether or not the vtec solenoid is activated (this is how the pcm judges if the vtec system worked or not)

Handy info:
Code P0522 will set when the sensor output voltage received by the PCM is 0.18v or lower for at least 2 seconds.

Wire colors
Green/yellow - sensor ground
Yellow/blue - Reference voltage (it's a simple sensor, so I'd expect to measure 5v here)
White/black - sensor output voltage to PCM

IMO it's probably a sensor or wiring type of issue, not a mechanical failure in the vtec system, valve, or engine.

ezone

Oh yeah I'm using service info for USA, but I don't think that makes any difference for this.

DRTYDZL

Awesome, thanks very much for this. Will report back tomorrow after testing

DRTYDZL

Ezone you were correct, as soon as I unplugged the EOP the code changed. Turns out my sensor was faulty.

On the note of the sensor, Honda charges 200 CAD for this sensor, the parts guy I was speaking to on the phone laughed when I told him what I needed the EOP sensor, hes like your better off buying a new vtech solenoid for 235 which comes with the sensor.

I didnt purchase either from the dealer, went to our local you pull it junkyard and got 2 complete Vtech solenoid units for $24. Installed the sensor today and chk light gone.

Ezone youre a good man, thank you for your help!!