SureTrack Community Fix: Pulsing Cruiser

Most mechanics want to resist the urge to just swap parts when presented with a diagnostic code and instead do the diagnostic work to find the actual cause. SureTrack community member locustpoint had a PT Cruiser in their shop that was pulsing when driving and had a code P0339 for the crankshaft sensor. Testing showed the sensor to be good. They posed the question to the community, and with the help of fellow community member Ericsautomotive and others, they were able to resolve the issue quickly.

The following Community Fix summarizes the interaction between members of the community that led to the solution.

Vehicle
2003 Chrysler PT Cruiser GT 2.4L

Title
Engine pulses, replaced crankshaft position sensor.

Complaint
Customer complains that check engine light is on and engine pulses.

Diagnostic Steps Performed/Parts Replaced
Verified customer’s complaint and found that above 2500, engine starts to rev up and down, or pulses, like you’re hitting the throttle on and off. Found code P0339: Crankshaft Position Sensor Intermittent. Checked crankshaft position sensor (CKP) signal, ground, and 5Vref and found all good. Scoped signal wire while running and everything looks fine. Checked CKP sensor signal while engine was pulsing and it was within spec. What could cause this?

Best Answer from Community Member Ericsautomotive
I’ve had more than one Chrysler product set a CKP code when the Cam sensor was at fault.

Cause
After checking Cam and CKP signals with scope and they both looked good. Car still kept setting code P0339 so we replaced the crank sensor. Runs fine now. Go figure. Thanks for the help.

Correction
Replaced Crankshaft Position Sensor, cleared code and test drove vehicle. Pulsing is gone and check engine light did not come back on.