Jeep Liberty Won’t Start Intermittently: Diagnosis and Solutions

ByThe Answerlode Editorial Team

Diagnosing Intermittent Starting Issues in Your Jeep Liberty

Intermittent starting problems are genuinely maddening to chase. The Liberty fires right up Monday morning, then leaves you stranded Tuesday afternoon, and by the time you get it towed to a shop it starts perfectly and throws no codes. Here’s how to work through it systematically.

Step 1: Nail Down the Exact Symptom

This distinction matters more than anything else in the diagnosis. Listen closely when it fails:

  • No crank: The engine doesn’t turn over at all — you hear clicking, a single clunk, or nothing.
  • Crank but no fire: The starter engages and the engine spins over normally, but it won’t ignite.

These two symptoms point to completely different systems. Getting this right saves a lot of wasted effort and money.

Step 2: Pull Fault Codes Without a Scanner

Jeep Liberty models let you read stored diagnostic codes using just your key. No scanner needed.

  • Start with the key out and the engine off.
  • Turn the key to the ON position — don’t crank it.
  • Turn it back to OFF.
  • Repeat two more times, ending in the ON position. The full sequence is OFF-ON-OFF-ON-OFF-ON.
  • Watch your odometer display. Codes appear as numbers; “Done” means nothing is stored.

If nothing shows up, turn the key off, wait ten seconds, and try again. The timing can be finicky. Write down every code that appears — they’ll point you toward the specific system causing the problem.

The Crankshaft Position Sensor: Start Here

The crankshaft position sensor (CPS) is the leading cause of intermittent no-start on the Liberty. It signals the engine control module when to fire the spark plugs. No signal from the CPS means no spark, which means no start.

What makes this sensor especially tricky is something called thermal failure. The sensor tests fine when the engine is cold but fails once things heat up. The classic pattern: the Liberty starts without issue first thing in the morning, then refuses to fire after a short drive or after sitting in the sun for an hour. Let it cool completely and it starts right up. That cycle is a strong indicator of a failing CPS.

The sensor sits on the right rear side of the cylinder block. Codes P0320, P0335, or P0336 all point toward it. Before you replace the sensor, though, inspect the wiring harness first. Check the connector for corrosion and confirm it’s fully seated. A slightly loose or dirty connector can produce exactly the same symptoms as a dead sensor — and reseating it takes two minutes.

Other Causes to Rule Out

If the CPS checks out, these are the other common culprits:

  • Dead or weak battery: Insufficient voltage can prevent the starter from engaging and stop the computer from firing the plugs. Get it load-tested, not just measured with a voltmeter — a weak battery often reads fine at rest and collapses under load.
  • Corroded or loose battery terminals: Poor connections are one of the most common causes of intermittent no-crank. Quick to check and easy to fix.
  • Faulty starter motor: A failing starter may work sometimes and not others, often cranking more slowly before it gives up entirely.
  • Ignition switch failure: A worn switch can break the starting circuit intermittently. Wiggling the key gently while trying to start is a fast field test for this.
  • Fuel pump relay: A failing relay cuts power to the fuel pump intermittently. This produces a crank-no-fire condition rather than a no-crank.

Next Steps

Run the key-cycle code pull first. If codes appear, chase those before touching anything else. No codes but the problem persists? Get the battery load-tested and the charging system checked — weak electrical supply causes a surprising number of intermittent gremlins that never set a code. A shop with a proper scan tool can also watch live crankshaft position sensor data while cranking, which is the fastest way to catch a flaky CPS before it starts storing codes on its own.

Sources

Related Articles

Jeep Cherokee Key Fob Not Detected: Troubleshooting Guide
Engine Cranks But Won’t Start? How to Diagnose Fuel Pressure Problems
2005 Honda CRV Won’t Start? Complete Fuel, Spark & Injection Diagnostics
Why Multiple Service Messages Appear at Once on Your Jeep Cherokee
B2101 Error Solved: When Your Chrysler Avenger Starts Remotely But Not Manually

Similar Posts