9 Warning Signs of CPS Failure on 7.3 Powerstroke Engines

Some of the most common 7.3 Powerstroke CPS failure symptoms are engine misfiring, random engine shutdown, engine surging, poor engine power, blinking check engine light, etc.

Here in this guide, we’ve explained all the common engine problems that occur due to CPS malfunction.

Along with that, we’ve also put together a guideline on what action you should take immediately upon noticing such symptoms and what causes the CPS to go bad. 

At a Glance: 7.3 Powerstroke CPS Failure Symptoms & Causes

Engine MisfiringThe CPS sends false signals to the ECU.
Random Engine ShutdownECU adjusting the fuel injection based on wrong signals from the CPS.
Engine SurgingBad CPS giving inaccurate data about the crankshaft’s position to the ECU.
Poor Engine PowerECU adjusting wrong ignition and injection timing due to faulty CPS.
Low Fuel EfficiencyA bad CPS prevents the connection between the terminals and wires.
Rough IdleECU setting wrong ignition and fuel injection timing due to CPS malfunctioning.
Check the Engine Light OnCPS going bad.
Long CrankWrong signals from malfunctioning CPS.
Bad TachometerA bad CPS prevents connection between the terminals and wires.

Also Check: Ford 7.3 Powerstroke Bad IPR Sensor Symptoms.

9 Common Symptoms of CPS Failure on 7.3 Powerstroke

Here are all the major CPS failure symptoms that you should never ignore –

1. Engine Misfires

This is one of the primary symptoms of a bad CPS (Crankshaft Position Sensor). Every modern engine management system now comes with CPS which is responsible for sending the ECU signals about the position and speed of the crankshaft. And based on that, ECU sets the fuel injection timing and ignition. 

But when the CPS fails, it sends false information about the crankshaft’s speed and position. As a result, the ignition and fuel injection happen at the wrong timing, leading to engine misfires.

Prolonged exposure to engine misfire can damage the catalytic converter and some other engine components. 

However, a bad CPS isn’t the only cause leading to engine misfires, here are some other reasons for that –

  • Faulty spark plugs
  • Ignition coil problems
  • Ignition timing issues
  • Clogged injectors
  • Bad fuel pump
  • Vacuum leaks
  • MAF sensor failure

2. Random Engine Shutdown

This is also known as engine stalling and is a pretty common sign of bad CPS. As mentioned earlier, the ECU relies on the CPS for information about the crankshaft position and speed. 

Thus, when the CPS goes bad, it loses track of the crankshaft’s position causing the ECU to adjust the ignition and fuel injection timing inaccurately. And that’s what leads to sudden engine stoppage or stalling. 

When the CPS malfunctions, the engine can stop all of a sudden in the middle of the highway, and might take a long time to start after that. However, in the worst case, the engine might not start at all.

Apart from bad CPS, some other reasons that lead to engine stalling are –

  • Bad fuel pump
  • Clogged fuel filter
  • Clogged air filter
  • Bad ignition coil
  • TPS malfunction
  • Low compression

3. Engine Surging

The CPS delivers the crankshaft’s position data to the ECU of the engine and based on that data the ECU synchronizes the fuel injection process. In other words, based on the CPS data, the ECU delivers the needed amount of fuel at the right time. 

But when the CPS malfunctions, it either sends the wrong data to the ECU or doesn’t communicate at all, resulting in inaccurate fuel delivery at the wrong timing. That’s what leads to engine surging. 

Furthermore, in some cases, when the ECU detects an abnormality in the CPS functioning, it tries to take data from the other sensors which can lead to unbalanced air-fuel mixture and incomplete combustion, causing the engine to surge.

However, a faulty CPS isn’t the only reason for engine surges, here are some others:

  • Faulty ignition component
  • Throttle body issues
  • Intake manifold gasket leaks
  • Clogged fuel injectors
  • Faulty fuel pressure regulator
  • Faulty mass airflow sensor

4. Poor Engine Power

If the ECU detects the malfunctioning of CPS, it can put the engine to default mode which will limit the power output.

Plus, since the ECU relies on the CPS and if the ECU doesn’t detect the CPS malfunctioning and acts in accordance with the data provided by the ECU, that can result in inaccurate fuel delivery and injection timing, leading to low engine performance.

You might feel the vehicle isn’t picking up speed as well as it used to do before, the towing capacity might get reduced significantly, the vehicle might not respond to acceleration properly, etc. 

Here are some other common causes leading to low engine power –

  • Worn-out spark plugs
  • Malfunctioning ignition coils
  • Compression loss
  • Timing belt issues
  • Exhaust restrictions
  • Throttle position sensor failure

5. Low Fuel Efficiency

When the CPS goes bad, you might notice a significant drop in fuel mileage. It happens because of false signals that the CPS sends to the ECU. When the ECU gets inaccurate data about the crankshaft’s position, it prepares the fuel injection and ignition at the wrong timing which leads to incomplete combustion.

As a result, the engine consumes more fuel than needed causing the mileage to decrease dramatically. However, low fuel efficiency is a common sign of many major engine issues such as –

  • Injector nozzle clogging
  • Clogged filters
  • Bad fuel pump
  • Worn-out engine component
  • Clogged injectors

6. Rough Idle

A malfunctioning CPS tends to provide false information, as a result, the ECU will set the injection and ignition timing wrong, leading to a rough idle.

Not only that, the ECU depends on the CPS, also for maintaining a stable idle speed. But that as well gets disrupted by false signals by the CPS, which results in rough idle.

If you’ve never experienced rough idle before and don’t know what it feels like, let us help! You’ll find the vehicle vibrating abnormally and the engine wouldn’t respond to the throttle as well as before. 

Some other causes of rough idle are –

  • Idle air control valve issues
  • Dirty throttle body
  • Bad throttle position sensor
  • Compression issues
  • Clogged filters

7. Check the Engine Light On 

The first symptom you’d see if anything is wrong with the engine is the blinking check engine light. As you know, the ECU keeps tabs on most of the engine operations and whenever it detects something’s not operating well, it triggers the check engine light to let the driver know the engine needs attention. 

The same goes for the CPS. If it’s malfunctioning or has gone bad totally, the first sign is the check engine light on. 

8. Long Crank

The wrong signal from the CPS to the ECU will increase the cranking time while starting the engine. And in the worst-case scenario, the engine might not even start at all. So, if you notice the vehicle is cranking frequently, probably the CPS is to blame. 

9. Tachometer Not Working 

The tachometer is what measures the rotational speed of the engine and it does that based on the signals from the CPS. Thus, when the CPS goes bad, it prevents the connection between the terminals and wires, as a result, the tachometer might not work. 

What to Do If You Find the CPS is Malfunctioning on 7.3 Powerstroke

If you notice any of the above-mentioned symptoms and guess that your CPS is malfunctioning, here is what you should do immediately –

Step 1 – Using Trouble Code Scanner

Scan the engine with a trouble code scanner, if there is any issue in the engine, the scanner will show some codes which indicate the issue in the engine. For bad CPS you might see the following trouble codes –

  • P0335
  • P0336
  • P0337
  • P0338
  • P0340

Step 2 – Visual Inspection

If you find any codes that indicate something is wrong with the CPS, you want to do a thorough visual inspection. Look for loose wire connections or damaged wires or dirt accumulation around the CPS. 

Step 3 – Take the Expert’s Help

After visual inspection, if you find anything wrong like damaged wire, corrosion, worn-out engine components, etc. have an expert mechanic take a look at the engine and make necessary repairs. 

What Causes the CPS to Go Bad Early in the 7.3 Powerstroke Engine?

The reasons for CPS going bad are many, but the common reasons are these-

● Electrical Problems 

One of the most common causes of CPS failure is a disruption in the signal flow between the CPS and ECM. And the disruption happens due to short circuits, damaged wirings, open circuits, etc.

● High Engine Temperature

The CPS is exposed to the engine heat. Thus, when the engine temperature increases, the CPS gets affected. And extremely high temperatures can damage it.

● Contaminants and Vibration

It’s normal for oil, dirt, and debris to accumulate around the CPS and they need to be cleaned on a regular basis. Otherwise, the contaminants might not allow the CPS to detect the crankshaft’s position accurately. Plus, high vibration of the engine can also cause the CPS to malfunction. 

● Wrong Installation 

Not installing the CPS properly can make it send false signals or not work at all, which is very obvious. Not only that, mishandling the CPS while installation can cause it to go bad.

Further, any damage to the wire and sensor during repair or installation can cause the CPS to go bad for good.

Video: Ford 7.3L Powerstroke Camshaft Position Sensor Installation


What is the life expectancy of 7.3 Powerstroke CPS?

If maintained well, a CPS should last around 150,000 miles or 10 years without any issues. 

Can you drive with a bad CPS?

An engine might operate even with a bad CPS, however, it can be very dangerous. A bad CPS might cause the engine to act unusual all of a sudden which can be a headache if you’re driving on highways. 

Will the car start without a crank position sensor?

The CPS is the most important of all sensors and without this, the engine can’t run.

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