It leaks oil, I have figured out that I may need a new oil pressure sending unit. How do I get at it to replace it? do I have to remove the wiring harness? Is it easier to get at from the top or botto

I have done this on a 2003 Odyssey EX. The oil pressure switch is located on the oil pump assembly, which is behind the passenger side front wheel. There are 2 sensors - the oil pressure switch is the furthest one and least accessable. You need to pull off the connector, which is very tight. I used a pair of pliars with a cloth to twist it off. Be carefull not to damage the connector. There are 2 different switches available for the 2003, each with different tread sizes. I used a regular wrench to remove/install the switch, and it stopped the leak that prompted the repair. Another TIP: watch how long your wrench is, because you can catch the power steering pressure switch wiring harness and break the thin wires, leading to a much more expensive repair.... Next time I will disconnect the power steering pressure switch first and pay more attention. Or buy a shorter wrench.... Good luck!After you remove take to Auto part store and match up with a new one.Adeep well socket may also work.here's another site I found on removing.

1. Locate the oil pressure sending unit on the engine.
2. Note the anti-theft code and radio presets for the radio.
3. Disconnect the negative battery cable.
4. Disconnect the sending unit electrical harness.
5. Using a pressure switch socket, deep-well socket or wrench, loosen and remove the sending unit from the engine.

To install:

1. Apply a liquid thread sealant to the sending unit and install the sending unit in the engine and tighten securely.
2. Attach the electrical connector to the sending unit.
3. Check the engine oil level and top off as necessary.
4. Connect the negative battery cable.
5. Enter the anti-theft code and radio presets for the radio.
6. Start the engine, allow it to reach operating temperature and check for leaks.
7. Check for proper sending unit operation.

It is really hard to get to, but really easy to change.

Unhook the battery cable so you don't blow the new one when you install it. Depending on the location, you may have to remove the oil filter to be able to access the sensor.

Unplug the wire off the end of the sensor, slip a socket onto the old sensor, and unscrew it like you would a spark plug. Before you out the new sensor in make sure it has Teflon tape on the threads. I always a little more than what comes with it.

Screw in the new sensor "hand tight" - then 1/4 to 1/2 turn past hand tight; do not over tighten. Plug the wire on the end. If you removed the oil filter, replace it with new one. Last step - replace the battery cable.

first need to buy oil pressure sending unit 3/8 deep socket remove oil pressure sending unit you need teflon tap sealer for oil sending unit threads.okay to replace oil pressure sending unit.you need safe raise support vechicle locate oil pressure sending unit next to the oil filter.disconnect oil pressure sending unit wire connector then use oil pressure sending unit 3/8 socket remove the sending unit.then take new oil pressure sending unit use teflon tape white plumbers tape or use thread sealer apply to the oil pressure sending unit threads then install new oil pressure sending unit and reconnect electrical connector to sending unit.then crank engine check for oil leak if all is good lower vechicle back to ground wait several minutes check engine oil level.you good to roll.

Click on link to view.http://www.autozone.com/autozone/repairinfo/repairguide/repairGuideContent.jsp?fromSearchPage=true&pageId=0996b43f80cb42b6&partName=Oil+Pressure+Sensor&partId=0996b43f80cb42b6

Oil pressure can be checked at the sending unit passage with an externally mounted mechanical oil pressure gauge. To get accurate results from the test, make sure you follow the manufacturer's recommendations and compare your findings to specifications.
Testing the Oil Pressure Gauge

• Test the gauge by grounding the wire that leads to the sending unit on the block.
• When the wire is disconnected from the sending unit with the key switch on, the needle on the oil pressure gauge should be either all the way high or all the way low. Grounding the wire should make the needle move to the opposite side of the gauge from where it was before the wire was grounded. If the vehicle is equipped with an oil pressure light, touching the wire to ground and then removing the wire from ground should turn the light on and off.
• If either happens, the gauge and wiring are good and the sending unit is at fault.

Testing Oil Pressure
Pressure can be tested by temporarily installing an oil pressure gauge in place of the sending unit. Before testing, look up the oil pressure specifications for your vehicle in the appropriate service manual.

• Bring the engine up to operating temperature.
• Now shut the engine off.
• Locate the oil pressure sending unit; usually it is on the lower side of the engine block.
• Disconnect the wire from the sending unit and use an open ended wrench to remove the sender. Using pliers can damage the unit.

An oil pressure sending unit is removed with a special socket. Courtesy of Chrysler Corporation.

• Tighten the oil pressure test gauge into the hole in the block where the sender was removed.

Measuring oil pressure. Reprinted with permission.

• Check the engine's oil level and fill, if required.

WARNING Be extremely careful when working near a running engine. Always wear safety goggles or glasses with side shields when working around moving machinery and be sure that your clothing is not loose.

• Now turn the engine on and check the oil pressure on the gauge.
  • Watch as the engine warms to note any excessive drops due to temperature.
  • Make sure the engine speed is set to specifications for testing pressure.
  • If necessary, us a tachometer and adjust the engine idle speed.
• Record the measured oil pressure, then turn off the engine.
• Compare the test results with the manufacturer's specifications.
  • If the oil pressure is within specifications, this shows that the oil pressure sending unit may not be working correctly.
  • In many cases, replacing the oil sending unit will correct the problem.
• After the test is complete, reinstall the oil pressure sending unit, start the engine, and confirm there are no leaks.

With jeep oil pressure sending units, it is common. They tend to leak, with oil coming out of the wire connector. You will have to replace that sending unit.

This is the oil pressure sending unit.

The easiest thing to do is get a new one, remove the old wone, and install the new one.

The oil is supposed to be kept separate from the electrical part, but sometimes they spring an internal leak. Replacing is easier than trying to get really specific about just where the oil is coming from. And once you do get specific, you almost always reach the same finding: a new unit is needed.

if engine is idling at proper RPMS. then you are dealing with low oil pressure or a faulty oil pressure sending unit.

Oil Pressure Switch Operation:
Information relay unit for the indicator light or gauge on instrument panel. It contains a diaphragm that responds to changes in oil pressure. When the oil level is over a pre-set limit, the diaphragm opens the switch, turning off the light. When level is below the pre-set limit, the dash light comes on. In later model cars, if the oil pressure drops, the switch turns off the fuel pump, to stop the engine and limit damage to internal parts. Oil pressure switches can be grouped into two categories, units for electrical gauges and for mechanical gauges.

Oil pressure can be checked at the sending unit passage with an externally mounted mechanical oil pressure gauge. To get accurate results from the test, make sure you follow the manufacturer's recommendations and compare your findings to specifications.
Testing the Oil Pressure Gauge

• Test the gauge by grounding the wire that leads to the sending unit on the block.
• When the wire is disconnected from the sending unit with the key switch on, the needle on the oil pressure gauge should be either all the way high or all the way low. Grounding the wire should make the needle move to the opposite side of the gauge from where it was before the wire was grounded. If the vehicle is equipped with an oil pressure light, touching the wire to ground and then removing the wire from ground should turn the light on and off.
• If either happens, the gauge and wiring are good and the sending unit is at fault.

Testing Oil Pressure
Pressure can be tested by temporarily installing an oil pressure gauge in place of the sending unit. Before testing, look up the oil pressure specifications for your vehicle in the appropriate service manual.

• Bring the engine up to operating temperature.
• Now shut the engine off.
• Locate the oil pressure sending unit; usually it is on the lower side of the engine block.
• Disconnect the wire from the sending unit and use an open ended wrench to remove the sender. Using pliers can damage the unit.

An oil pressure sending unit is removed with a special socket. Courtesy of Chrysler Corporation.

• Tighten the oil pressure test gauge into the hole in the block where the sender was removed.

Measuring oil pressure. Reprinted with permission.

• Check the engine's oil level and fill, if required.

WARNING Be extremely careful when working near a running engine. Always wear safety goggles or glasses with side shields when working around moving machinery and be sure that your clothing is not loose.

• Now turn the engine on and check the oil pressure on the gauge.
  • Watch as the engine warms to note any excessive drops due to temperature.
  • Make sure the engine speed is set to specifications for testing pressure.
  • If necessary, us a tachometer and adjust the engine idle speed.
• Record the measured oil pressure, then turn off the engine.
• Compare the test results with the manufacturer's specifications.
  • If the oil pressure is within specifications, this shows that the oil pressure sending unit may not be working correctly.
  • In many cases, replacing the oil sending unit will correct the problem.
• After the test is complete, reinstall the oil pressure sending unit, start the engine, and confirm there are no leaks.

Check your oil level in the engine. Oil pressure will read this way when the oil level is getting low...