Jeep Liberty Won’t Start Intermittently: Diagnosis and Solutions

ByThe Answerlode Editorial Team

Diagnosing Intermittent Starting Issues in Your Jeep Liberty

An intermittently starting Jeep Liberty is one of the most frustrating problems to diagnose, especially since it may start fine one day and refuse to cooperate the next. Understanding the difference between a no-crank condition (engine doesn’t turn over at all) and a no-fire condition (engine cranks but won’t ignite) is your first step toward identifying the real culprit.

Step 1: Determine the Exact Symptom

When your Liberty won’t start, pay close attention to what actually happens:

  • No crank: The engine doesn’t turn over at all; you hear only clicking or nothing
  • Crank but no fire: The starter motor engages and the engine turns over normally, but it refuses to fire up

Each symptom points to different potential causes, so being specific will save you time and money when troubleshooting.

Step 2: Check for Fault Codes

Jeep Liberty models allow you to read diagnostic trouble codes using just your key, without any special equipment. Here’s how:

  • Make sure the engine is off and the key is out of the ignition
  • Turn the key to the ON position without starting the engine
  • Turn the key back to OFF
  • Repeat this sequence two more times, ending with the key in the ON position
  • Watch your odometer display; fault codes will appear as numbers or the word “Done” if no codes are present

If this doesn’t work the first time, turn the key to OFF, wait 10 seconds, and try again. This procedure can be finicky, but it’s reliable once you get the timing right. Write down any codes that appear, as they’ll point you toward the specific system causing the problem.

The Crank Position Sensor: The Most Common Culprit

The crankshaft position sensor (also called the crank position sensor or CPS) is the leading cause of intermittent starting issues in Liberty models. This sensor tells your vehicle’s computer when to fire the spark plugs. When it fails, the engine may not recognize the proper firing sequence and refuse to start.

What makes this sensor particularly problematic on Jeep Liberties is something called thermal failure: the sensor works fine when the engine is cold but fails completely once the engine warms up. This explains why your Liberty might start without issue in the morning but refuse to fire up after a few hours of driving or sitting in the sun.

The crank position sensor is located on the right rear side of the cylinder block. If your fault codes point to this sensor (typically P0320, P0335, or P0336 codes), it’s likely the source of your problem. However, before you replace it, check that the wiring harness connected to the sensor isn’t damaged and that the connector is fully seated and corrosion-free. Sometimes simply reseating the connection or cleaning corrosion from the sensor terminals solves what looks like a failed sensor.

Other Causes to Rule Out

While the crank position sensor is the most common cause, other issues can produce similar symptoms:

  • Dead or weak battery: If the battery can’t supply adequate voltage, the starter may not engage or the computer may not fire the spark plugs
  • Faulty starter motor: A starter that’s failing intermittently may crank slowly or not at all
  • Corroded or loose battery terminals: Poor electrical connections prevent current from reaching the starter and ignition system
  • Ignition switch failure: A worn ignition switch can prevent the key from engaging the starting circuit
  • Fuel pump relay: A failing relay may cut power to the fuel pump intermittently

Next Steps

Start by checking your fault codes using the key-on-off method described above. If codes appear, they’ll guide your repairs. If no codes are present but the problem persists, have the battery voltage tested to rule out electrical issues. A professional mechanic can also perform a more thorough diagnostic with specialized scanning equipment if the problem remains elusive.

Intermittent starting problems are time-consuming to diagnose, but methodically working through these steps will eventually reveal the root cause and get your Liberty back on the road reliably.

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