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Pete
Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 29096
Experience:  14 years GM dealer Technician.
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I cannot get my monitors for O2 heater and eval to reset

Customer Question

I cannot get my monitors for O2 heater and eval to reset after dead battery
JA: Did you test the battery with a voltmeter? And have you ever changed one before?
Customer: I installed a new battery
JA: What is the model/year of your Chevy?
Customer: 1999 c2500
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: since smog station said 2 monitors were not set I have driven about 400 miles. I put a new gas cap on. I drove for 10 minutes at 50mph 3 times. I spun a donut both left and right ( chevy maintenance man told me that one)
JA: Anything else you want the mechanic to know before I connect you?
Customer: it is a dual fuel vehicle so there is also a computer for natural gas. The CNG fuse is out as is the tank
Submitted: 2 months ago.
Category: Chevy
Expert:  Pete replied 2 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Make sure you are not disconnecting the battery or clearing codes as this resets the process all over again.The procedure below is a procedure I have followed several times in the past before to get the monitors to run faster.

Cold Start
The barometric pressure (BARO) is more than 81 kPa.
The engine coolant temperature (ECT) is between (41-86°F).
The intake air temperature (IAT) is between (41-86°F).
The start-up ECT and IAT are within (16°F) of each other.
The battery voltage is between 9-16 volts.
The fuel level is between 15-85 percent.

Important: Whenever the ignition is turned ON, ignition positive voltage is supplied to the HO2S heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure.

Turn OFF all of the accessories,
Set the vehicle parking brake.
Verify the transmission is in Park for automatic transmissions and Neutral for manual transmissions.
Start the engine and allow the engine to idle for 2 minutes.

Acceleration at part throttle to (55 mph) with this speed maintained until the engine reaches operating temperature. This may be up to 8 minutes depending on the start up coolant temperature.
Continued operation under these conditions for an additional 6 minutes.

Acceleration at part throttle to (45-55 mph) with this speed maintained for 2 minutes.
Deceleration to (0 mph).
Engine idling for 2 minutes while the following criteria is maintained:
The service brake is depressed.
The automatic transmission is in drive.
The manual transmission is in neutral with the clutch pedal depressed

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated ( should be a link to click on here or above).You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete