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ChevyTech · 10-15-2007, 03:24 PM

Check for corrosion at the ECM connectors.

Here are some tests you can do:
Test the reference voltage to the TPS, MAP or BARO sensor. This tests terminal 21 voltage. It should be 5 volts. 4 to 6 volts is considered acceptable.

With the O2 sensor unplugged, and the engine idling - Test the voltage on the purple ECM wire for the O2 sensor. I can’t remember the exact value but it should be around .4 to .6 volt.

Reply back with your results.

10-15-2007, 03:24 PM	#5
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,621	Re: Code #41 and #55 Check for corrosion at the ECM connectors. Here are some tests you can do: Test the reference voltage to the TPS, MAP or BARO sensor. This tests terminal 21 voltage. It should be 5 volts. 4 to 6 volts is considered acceptable. With the O2 sensor unplugged, and the engine idling - Test the voltage on the purple ECM wire for the O2 sensor. I can’t remember the exact value but it should be around .4 to .6 volt. Reply back with your results.