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Discussion Starter · #1 ·
Hi, I recently purchased a 2007 G6, I came across this site and never thought there was a community dedicated solely to the G6 and I was excited to join up! I am now going through the process of trying to register it now, A day prior to bringing it in for inspection I unhooked the battery to clear a check engine light (Didn't have a OBD2 handy), I have had no issues with it since. When I brought it in to get inspected and the tech told me that it showed 4 not ready rejections (Catalyst, O2 Sensor Heater, Evap System, and O2 Sensor). He told me to put some miles on the car and the systems should show ready, I have driven over 250 miles today and nothing has changed, I even went and got an OBD2 reader to keep an eye on it and still no change. I had to go back and get another 10 day temp tag today and I would like to try and get this figured out, the only thought process I'm having right now is to replace the ECU and see if there is any change. I just wanted to know if there were any solutions out there, or if replacing the ECU is my best bet.

Thanks for your input.
 

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Discussion Starter · #2 ·
UPDATE: I did a little research on the ECU, I didn't realize it till now but the car was in a front end collision and the previous owners father did put a hood bumper and fenders on it, I overlooked it a few times but the ECU is mounted in front of the battery and the mount is broken and its kind of set in there. I will be removing tonight to inspect it for any serious damage.
 

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Clearing the ECU with either a battery disconnect or OBDII command will flag the tests you mention. You will need to drive it more across a range of rpm's for the tests to pass. Perhaps try the items listed below and check with your scan tool

General Motors Driving Cycle (obdii.com)

General Motors Driving Cycle
A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:

  1. Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
  2. Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
  3. Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
  4. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
  5. Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
  6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
  7. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
  8. Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
Reprinted on OBDII web site courtesy of General Motors Corporation
 

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Discussion Starter · #4 ·
Clearing the ECU with either a battery disconnect or OBDII command will flag the tests you mention. You will need to drive it more across a range of rpm's for the tests to pass. Perhaps try the items listed below and check with your scan tool

General Motors Driving Cycle (obdii.com)

General Motors Driving Cycle
A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:

  1. Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50°C (122°F) and within 6°C (11°F) of the ambient air temperature at startup. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.
  2. Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire and if closed loop is achieved, Fuel Trim.
  3. Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.
  4. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.
  5. Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
  6. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3.
  7. Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.
  8. Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
Reprinted on OBDII web site courtesy of General Motors Corporation
Did some looking around and found this, going to try it tonight luckily I work late so the highways will be somewhat empty, thanks for the help
 

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Discussion Starter · #5 ·
Did some looking around and found this, going to try it tonight luckily I work late so the highways will be somewhat empty, thanks for the help
Also found an affordable set of O2 sensors on Amazon that I ended up ordering, the check engine light came back on with a 0420 code so I’m hoping it will help with that
 

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Your scan tool should be able to help with the O2 sensors. The pre-cat sensors should be rapidly moving up and down like a sine wave. This is what the ECU uses to adjust the fuel trim. The post cat sensors should be relatively flat. This basically shows the CAT is functioning. If the post cat sensor is moving too much then the sensor may be good but the CAT bad.

Hope the new sensors fix the problem
 

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Discussion Starter · #7 ·
Your scan tool should be able to help with the O2 sensors. The pre-cat sensors should be rapidly moving up and down like a sine wave. This is what the ECU uses to adjust the fuel trim. The post cat sensors should be relatively flat. This basically shows the CAT is functioning. If the post cat sensor is moving too much then the sensor may be good but the CAT bad.

Hope the new sensors fix the problem
thanks appreciate the help
 
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