CAm Position Sensor 7.3 CPS Symptoms

Cam position sensor — 7.3 CPS was one of the first parts I replaced on my 2002 7.3 Powerstroke diesel.

The truck had 202,000 miles on it and was a little neglected. So I took out the old grey version—the original black CPS had long since been replaced—and threw it in my glove box as a spare.

Then I replaced it with this new purple/blue/dark grey 7.3 CPS.

More on the 3 different 7.3 CPS color versions later...

Cam Position Sensor 7.3 CPS
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7.3 CPS - Cam Position Sensor Function

Simply put, the 7.3 cam position sensor identifies which cylinder is at top dead center—the combustion stroke. Knowing this allows the engine power control module (PCM) to adjust fuel injection timing to provide smooth combustion to your diesel truck.

And that simply means that it helps your 7.3 Powerstroke diesel engine deliver fuel to the right cylinder at the right moment in the timing sequence.

Here's how it does that:

The inserted end of the 7.3 CPS is a magnet. The magnet's job is to sense the spokes and gaps (windows) on the camshaft wheel. Since the cylinder #1 and cylinder #4 indicator windows are narrower and wider, respectively, than the other windows on teh cam wheel, the 7.3 cam sensor can tell which cylinder is about to hit top dead center—TDC.

Then the PCM can deliver the fuel at the precise moment it's needed. It also helps in adjusting things like RPM to ensure smooth idle and operation of the engine.

So, guess what happens if your 7.3 CPS is malfunctioning?

7.3 Cam Position Sensor Symptoms

7.3 Powerstroke CPS symptoms include:

  • Rough idle
  • Hard start
  • Spontaneous stalling...

Dying at idle over a period of weeks or months can signal an imminent 7.3 CPS failure.

  • Unexpected and sudden failure.

Failed 7.3 CPS sensors have left many 7.3 Powerstroke drivers broken down along the side of the road.

One minute you'll be driving down the road with no issues and the next your trusty 7.3 liter diesel will simply dies. Then your engine will crank but not start.

Because if your 7.3's cam sensor is toast, it can't send a signal to the PCM. And if the PCM doesn't know where the cam is in the cylinder rotation it won't send an injector signal to the Injector Driver Module (IDM). Then your injectors won't fire and your truck won't start.

This is the exact scenario that has many 7.3 Powerstroke owners, myself included, carrying a spare CPS in our glove boxes.

And one quick way to tell if it's your cam sensor is...

  • Tach needle doesn't move during cranking.

During cranking, the tachometer needle on a pre 2002 7.3 Powerstroke won't move. A telltale sign that your 7.3 cam sensor has failed.

After 2002 the 7.3 diesel's instrument cluster changed and the "dead" tach was no longer an indication that the CPS had failed.

  • Idle Miss

Ford's new grey recall-replacement 7.3 CPS created a very noticeable idle miss. And injector #8 would fail a Cylinder Contribution Test (CCT) with a Diagnostic Trouble Code (DTC) p0284.

So, before you get drastic and replace an expensive injector, swap out your CPS.

But complete failure isn't the only 7.3 cps failure symptom to watch out for.

Because whichever cam position sensor 7.3 symptoms your truck has, a failure may not even throw a trouble code.

All of these are symptoms that your 7.3's cam sensor is about to fail.

Other CPS 7.3 Powerstroke symptoms include:

7.3 Cam Position Sensor Part Number

OEM Black 7.3 CPS

Part Number - F7TZ-12K073 or F7TZ-12K073-A

You might be able to find one of these around, but eBay sellers are charging a premium for the original black 7.3 CPS.

Ford Grey Recall-Replacement 7.3 CPS

Part Number - F7TZ-12K073-B

Cam Position Sensor 7.3 - Grey
Cam Position Sensor 7.3 - Grey

"NEW" Purple/Dark Grey/Blue 7.3 CPS

Part Number - F4TZ12K073C

Cam Position Sensor 7.3 - Blue
Cam Position Sensor 7.3 - Blue

7.3 CPS Repair Pigtail Part Number

Part Number - 7U2Z-14S411-SA

7.3 CPS Bolt Size and Torque

7.3 cam sensor bolt size - 10mm - M8x1.25x15mm

7.3 cam position sensor bolt torque spec - 18 lb/ft.

7.3 Cam Sensor Recall

After a lot of failures and unhappy 7.3 owners' complaints, Ford issued a safety recall—07S57—for the light grey OEM 7.3 powerstroke cam sensor.

In grand fashion, Ford's cure turned out to be worse than the disease and many owners went back to the original black version of the 7.3 cam sensor or just lived with occasional misses on the light grey CPS. (see light grey 7.3 CPS Symptoms above)

Until...

Ford released the new dark grey/"purple" CPS sensor mentioned above. 7.3 Powerstroke owners found that it provided better idle and increases in 7.3 MPG. This is the one I run in my truck and it smoothed things out considerably.

7.3 CPS Location

7.3 Powerstroke CPS Location

The Ford 7.3 Powerstroke cam position sensor location is at 11 'o clock just above the crankshaft damper. It's easier to access the 7.3 CPS from beneath the engine bay on the passenger side.

7.3 CPS Replacement

7.3 Cam Position Sensor Change Video

Here's Fordtekmakuloco's excellent 7.3 cam position sensor replacement video on YouTube.

How to change Cam Position Sensor 7.3

And here are the details on 7.3 CPS replacement:

Tools you'll need

  • 10mm socket
  • 3" socket extension
  • Socket Wrench
  • Torque wrench
  • 12-20" pry bar or long flathead screwdriver
  • Rust Breaker/Bolt release agent
  • Anti-seize
  • Dielectric grease
  • A little bit of new engine oil

Disconnect the negative battery cables

Any time you're working on your 7.3 diesel's electrical system, it's a good idea to remove the battery cables.

Remove the serpentine belt (Optional)

Some 7.3 owners remove the serpentine belt to make it easier to get a socket around the 7.3 CPS bolt head. But I've changed several of them with a 10mm socket and a 3" socket extension without having to remove the serp belt at all. It's up to you...

Disconnect the 7.3 CPS wiring harness connector

There's a retaining tab on the side of the connector. lift this tab away from the center of the connector a bit and then lift the connector off of the CPS.

I know, easier said than done.

So be careful because all the plastic in an almost 20 year old 7.3 diesel's gonna be brittle.

Loosen and remove the 7.3 CPS bolt

There are many ways to break a rusted or seized bolt free. Personally, I use some kind of bolt breaker like WD40 Rust Release or better yet, PB Blaster (Amazon Links). After stripping several bolts on my 200K plus mileage 7.3 Powerstroke, I hit most bolts with release before I try to remove them.

Spray a little rust release on about 30-60 minutes before you try to remove the CPS bolt.

After that, use your 10mm socket and 3" extension or a 10mm deep well with a 3/8" socket wrench to easily break the 7.3 bolt free and remove it.

Remove the 7.3 CPS

I've read where you should wiggle the CPS back and forth and then pull it out. I don't know about that because I've never been able to do it. My suggestion—20" pry bar and some GENTLE leverage applied behind the little CPS retaining bracket.

I think it's more that I can't reach my arm all the way up to the 7.3's CPS to grip it really well and the pry bar gives me the reach. Your results may vary...

Lubricate and install the 7.3 CPS

Put a little bit of fresh engine oil around your new cam position sensor and simply put it back into the CPS socket. This may take a little wiggling this time, so be patient and go slowly. But you'll feel the o-ring "bump" in and then it's seated.

Rotate the CPS retaining bracket so it's inline with the CPS bolt hole.

Whether your 7.3's CPS bolt came out easy or hard, do yourself a favor and apply some anti-seize to the new bolt before you torque it back in. You'll thank yourself the next time you have to change out your CPS.

Apply a little anti-seize to the CPS bolt threads. Then re-install the 7.3 CPS bolt and torque it to specs—18 lb/ft. Ys, you'll need a small 3/8" torque wrench for this.

Grease and reinstall the CPS pigtail connector

Push some dielectric grease down into the round female connector on your 7.3 CPS and clip the connector pigtail back onto the CPS.

NOTE: during the removal of my 7.3 CPS, the wiring harness broke loose from the cable retainer that was holding it to the water pump. I simply replaced that retainer with a zip tie and clipped the end.

The harness retainer is important because it keeps the wiring out of the way of the spinning serpentine belt.

Now, reattach your battery cables, fire up your 7.3 Powerstroke, and enjoy!

Leave a Comment:

MICHAEL HENMAN says

I’ve been bangin my head for 3 weeks ! My 2002 F-350 7.3 suddenly died waiting in the shade with the A/C on.Popped hood and coolant was everywhere (sinister remote coolant line split). I assumed sensor shut it down. Refilled degas tank, made it 4 miles from home a truck shut off. Called tow truck ( waited 2 hours in sun ), turned key over and drove it home….Ordered new CPS, installed, test drove, it shut down 2 miles from home !…..For grins, threw in ICP and another CPS. It idled for hour, headed for a Sunday outing, 2.2 miles from house shut down !!!……I give up

Reply
    Steve says

    Michael,

    I feel for you—been there done that! Sorry to hear the trouble you’re having… I read and reread your symptoms and it sounds like you are only dying after the engine heats up to operating temp. Cold oil is different than warm/hot oil in that it will flow past worn out o-rings pretty easily. From what I can find, assuming that you’ve dealt with the root cause of the leaking coolant first, check these things:

    HPOP reservoir oil level – If it’s up to 3/4″ from top you reservoir is okay. If not you may have 7.3 HPOP Leak. Check for oil in the Valley.
    I’ve read a couple forums calling out the IPR “coil”/solenoid failing and causing engine to die at running temp. Check the ICP duty cycle to determine if IPR is failing. Assuming you have access to a scan tool. I’ve used a Forescan light app on my iPhone with an ELM327 WIFI Wireless ELM327 OBD2 OBDII Auto Diagnostic Scanner Tool Adapter (Amazon Product Link)to check the ICP.
    Injector o-rings – if these fail, the injectors can’t get up the pressure once the engine gets hot and they won’t actuate, causing engine to die from fuel starvation.
    Some guys have done what you’ve done and chased it with new CPSs only to find out it was deeper fuel delivery or oil pressure related problems.

    Hope that helps.

    Steve

    Reply
Bill says

I have a 2001 F350 7.3 with 180,000 miles. It dies the other day just as it got to hwy speed. Checked code and it showed CPS failure. Keep a spare, replaced it. Truck started and ran. Took it out again after about a week, same thing. This time it restarted. Mow it has died while idling in the driveway. No failure code. Replaced CPS. same symptoms as a failed CPS, but no code and won’t start. Any suggestions as to where I should check next ?

Reply
    Steve says

    This is one of those times where, without codes or information, it’s hard to get yourself pointed in the right direction. Multiple CPS failures in a row, depending on what CPS brand you’re using, isn’t unheard of. However, since you also have no codes now, I’d check wiring harness, IPR Valve. IDM, UVCH, ICP Sensor, fuel heater blowing the #22 maxifuse… Without codes or some obvious leaks in the HPOP, etc.. you really are chasing the problem. Though, it could be a bad wiring harness to the CPS or electrical on the way there that’s shorting out a fuse or frying the CPS itself.

    Let me know what you find out as this is more common than you might think. Chasing CPSs… Not my favorite.

    Steve

    Reply
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