2014 CHEVY SONIC LT ECO TECH

Original Issue: check engine light code P0496 (purge valve)

After Replacing Purge Valve: Code U0100 (Lost Communication with ECM/PCM) & Power Steering Light

• NO REVERSE
• NO POWER STEERING
• RPM guage at zero

Sometimes no crank. Occasionally the car will start and show no symptoms for about 15 seconds then suddenly the RPMs will drop to zero, the power steering light comes on and loses power steering, and no reverse.

• Tried unplugging the new purge valve, reinstalled old purge valve, plugged, unplugged regardless no change.
• ​​Tried shaking purge valve wiring doesn't help.
• Checked for short circuit on the purge valve 2wire connector. No short
• Checked battery voltage and tested good. Sitting @ +/- 12.4 with engine off.
• Resetting OBD2 error code but code U0100 comes back immediately.

kind of at a loss at the moment. Tried to help a friend out and of course this happens.

if anyone can please help I would greatly appreciate it!


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This is LIKELY completely unrelated. When you have multiple issues at once the first thing you should check is battery voltage. Modules all have voltage parameters to run and when they see a voltage drop operation becomes sporadic.

Start with the basics, battery voltage, engine ground strap. I would like to add that just because theee isn’t a short in that circuit doesn’t mean it’s a good circuit. You need to check for a short, open, and then load testing the circuit to make sure the circuit is fully operating.