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Discussion Starter · #1 ·
Hey guys -
My oil pressure sending unit has quit. Family emergency going on so I am in a bit of a hurry to get this replaced ASAP and with the best part I can find, I am in no mood to futz around with sub-par replacements. Any advice is appreciated. Thanks.


Part Number is 56028 807AB for a 2002 4.7L.
 

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Grab a mopar. I got mine from the dealer. It wasn't too expensive. I also had to buy the sensor pigtail myself because mine was destroyed
 

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Mopar Nut
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I used an el-cheap-o from Amazon without issue, but that is always a gamble. I'll 2nd the "grab a Mopar", if you don't wanna mess around. If it's not leaking yet, replace it before it does - I have twice now seen them blow apart shortly after they failed....

Mother Mopar online shows about $53 for OEM, I'd expect your local dealer to be about the same.

I know a lot of guys look to Crown Automotive for OEM quality too. But don't go by my word on that - I've not used the Crown in this flavor. Summit lists Crown at $37.
 

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Yeah I want to say my mopar one from dealer was 55 and the damn pig tail was like 45 lol
 

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Screw that dealer crap...for the OPSU, just get the one that's cheap and close if you need it now.
Remember that the OEM unit failed too and at least the local parts store will hand you another one in 4 years when theirs fails but the dealer will certainly not.
 

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"Someone" Soem0 ???.......:wink2:
 

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Nope not me. Came with my dropped valve seat motor when I bought it. Someone JB welded the busted pigtail to the sensor lol. I was trying to find a pic of it but I was probably too mad when I was removing it
 

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It will certainly fail, OEM or not. That's why so many of us already know about it.
 

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Discussion Starter · #11 ·
Hot tip: you need a 27mm deep socket to swap out this sensor. Did not have one, cost me $10 to get one.

I swapped in the Crown replacement and put 500 miles on it the next day. Working fine, I think.
 

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I put a tee off the engine to allow a mechanical gauge along with the factory gauge to keep the computer happy. Did it when I replaced the heads to see oil pressure while cranking to prelube the lifters, it is scary to see just how little oil pressure there is hot at idle. My Crown replacement is still leak free after a year.
 

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Mopar Nut
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I put a tee off the engine to allow a mechanical gauge along with the factory gauge to keep the computer happy. Did it when I replaced the heads to see oil pressure while cranking to prelube the lifters, it is scary to see just how little oil pressure there is hot at idle. My Crown replacement is still leak free after a year.
Ditto. I run a Bosch oil psi and a coolant temp gauge (temp probe dropped in the air bleed port) under the hood. Same combo on most of my cars. '03-04 WJ's run a glorified idiot light for oil (With a single wire sending unit the gauge can literally only show psi present/not present - it may as well be a light bulb). The scale on that dash gauge literally means nothing. Someone may correct me, but I am pretty sure only '03-04 ran this worthless set-up, as I think the earlier models have a 3 wire sending unit. Besides that lying a** gauge, if I am poking about under the hood of a running car I am NOT looking at warning lamps and gauges on the dash board. I once had a rot hole on an oil pan give way on my '72 Dart at the drag strip - holding the RPMs at about 2500 in the pits while poking with a timing light, I seized up a 450hp 340-6bbl before I even noticed I was literally standing in a lake of oil. The few seconds I was pondering why it seemed like the engine was loading up and I think I smell hot oil is all took before it was all over. I've added the oil gauge under the hood ever since. Unless it is still under warranty, it at bare minimum gets an oil psi gauge.

In other news, the generic brand one wire sending unit I bought from Amazon for $17 still works fine a year later. But I still stand by my earlier comment to stick with Mopar to minimize gambling losses in general. I myself, am a gambler....
 

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I believe you're right, 03-04 has the idiot gauge. I do remember sitting in meetings at Jeep Truck Engineering back in the day listening to engineers discussing customer perception of gauge movement. Fuel gauges move faster closer to empty, temp gauges are damped to move s l o w, and most customers do not like an oil pressure gauge that moves around. Not to mention it saves .02 cents per vehicle having 2 less wires, lol.
Years ago a mechanical gauge saved my Suburban engine. I had replaced a timing chain set, about a week after on start up I noticed the gauge read zero. Immediately shut it down and started it again just to make sure, zero again. It was very cold (-16) and the thick oil sheared the pump drive shaft at the distributor.
 

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Discussion Starter · #15 ·
Well I had an interesting drive yesterday but I made it home. Started continually misfiring so I key danced and found P0523, OPSU voltage high. Also throwing P0300, P0301, P0302 but are they all related? Idk, suspect not.

Barely idles but can move if I keep the RPMs up.
 

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but are they all related? Idk, suspect not.
Only way I could relate them would be to suspect a ground. But I feel pretty certain that Gman's rig has clean grounds. A P0523 is most likely electrical related (as I also suspect Gman is NOT running 20w50 and most likely doesn't have plugged oil passages), but can't figure how that would cause misfires. I am with you on they are not related, and they popped up together based on pure co-inky-dink - failed OPSU and misfire(s) for unrelated reasons....

Unrelated to the above quote, I've now read enough about a failed OPSU now that I've ordered a 2nd to keep on the shelf. Especially since my current replacement is the el-cheap-o variety.....
 

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I believe you're right, 03-04 has the idiot gauge. I do remember sitting in meetings at Jeep Truck Engineering back in the day listening to engineers discussing customer perception of gauge movement. Fuel gauges move faster closer to empty, temp gauges are damped to move s l o w, and most customers do not like an oil pressure gauge that moves around. Not to mention it saves .02 cents per vehicle having 2 less wires, lol.
Years ago a mechanical gauge saved my Suburban engine. I had replaced a timing chain set, about a week after on start up I noticed the gauge read zero. Immediately shut it down and started it again just to make sure, zero again. It was very cold (-16) and the thick oil sheared the pump drive shaft at the distributor.
I had an 03 HO that fired it's warning light, and dropped the oil pressure to zero every now and then.
Naturally, when the light came on I stopped, and poked around the engine.
I couldn't see or hear anything nasty, so I got back in, fired it up, got full oil pressure, and drove on.

This went on for a few trips.
Eventually I got a breakdown truck, the driver mech explained wisely about the several things that could cause my problem.
His reasons seemed to lack logic.

I convinced myself there was a wire / connection was on the blink, and ignored the warning.
Inevitably, the engine sort of seized.

I sold it for scrap.

Eventually, I found out that if the pressure fell in a way the programmer didn't like, the gauge went to zero rather than the actual pressure.

Oil thinning when it got hot caused the problem.
If I'd have an oil temp gauge or a mech oil pressure gauge I wouldn't have lost the engine.

I'd been using an expensive specialist oil that would deglaze the bores, which, I hoped would solve a smoking problem cause by oil going through with crankcase ventilation.

I've shorted the ignition out through the oil idiot light switch on a number of cars to stop the engine starting until there's enough pressure to open the oil pressure switch.
 
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