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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet camero: Can't get the O2S monitor to set. No fault

Customer Question

Can't get the O2S monitor to set. No fault codes or Freeze frames showing on the scan tool. Has been run several hundred miles over a month of driving 60 miles round trips, at freeway speeds and slow stop and go traffic. 97 SS Camero with a 170,000 miles. new first stage O2 sensors
Submitted: 1 year ago.
Category: Chevy
Expert:  Tool Hut replied 1 year ago.
Hi, My Name is***** have over 20 years experience repairing vehicles. I am a ASE Certified Master Auto Technician. I am confident we can resolve your problem together.Please remember I don't know your skill level. I can't see, smell, hear, or touch the vehicle. It may take a few back and forth replies to get to a satisfactory resoloution. Try your best to respond with good detail so I can do the same.below I have inserted a procedure to force the monitor to run. I would suggest starting here. What was the reason for replacement?HEGO Monitor Not ReadyThe Heated Exhaust Gas Oxygen sensor monitor makes sure the oxygen sensors are functioning properly and are operating within their normal range. The monitor runs after the engine has reached normal operating temperature, and the vehicle is cruising at a specified speed for a specified length of time. This monitor will not run if there are any faults in the oxygen sensor heater circuit, if there are any pending oxygen sensor codes, or the engine coolant or vehicle speed sensors are not functioning normally.If the HEGO monitor is NOT ready, it will prevent the catalyst efficiency monitor from running, causing yet another Not Ready to be tallied against you!HEGO Drive CyclesThe following are some sample drive cycle requirements for the HEGO monitor to run:Ford: The HEGO monitor should run when the engine has reached normal operating temperature, the inlet air temperature is between 40 and 100 degrees F, and the vehicle is cruising at a steady 40 mph for four minutes.GM: GM uses a two-part HEGO monitor. The first part of the HEGO monitor runs after idling the engine for two and a half minutes with the A/C and rear defroster on. This checks the O2 heater circuit. After this, turn the A/C and defroster off, then accelerate at halt throttle to 5 mph and hold at a steady 55 mph for three minutes. This will complete the second half of the HEGO monitor that checks the responsiveness of the O2 sensors.Chrysler: Idle for five minutes (to reach closed loop operation). Then drive at a steady vehicle speed above 25 mph for two minutes. Stop and idle for 30 seconds. Then smoothly accelerate to 30 to 40 mph. Repeat the last two steps five times.Toyota: The HEGO monitor should run after idling the engine for nine minutes, then driving at a steady 25 mph for two minutes.

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