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Forum > Failed Smog Test > Question

Pontiac Vibe Won't Complete Emission Monitors

I have replaced the catalytic converter on my 2004 Pontiac Vibe. After driving the car 150+ miles to set the computer, the O2 sensor code and the EVAP code did not allow the car to pass smog check. I had both O2 sensors replaced, have driven the car 100+ miles, had the car tested, and the codes are still showing.

How do you reset the codes after replacing the O2 sensor? I have driven the car over 400 miles just to reset the computer. Do you have any suggestions? There is 179,600 miles on the car. I need a Pontiac Vibe drive cycle.


Answer:

It's important we first differentiate between clearing trouble codes and setting (completing) emission monitors. Emission monitors are internal self-tests which the ECU (engine control unit) performs to ensure engine emission system(s) are functioning properly. Trouble codes are data which  are created and stored in the ECU which identify specific emission components/systems which are defective or not functioning as required. It is important to note that a drive cycle may not complete if a vehicle's check engine light is ON and trouble codes are stored within the ECU. So before we begin a drive cycle, we need to ensure there aren't any trouble codes stored in the ECU.

If your Vibe is not passing the smog check because there are trouble codes in the ECU (you'll know this if the check engine light is ON, and more so, if you use a trouble code scanner), you'll need to clear the trouble codes either by disconnecting the battery and/or removing the ECU fuse(s), or you may use the more efficient way of clearing trouble code using a trouble code scanner ($30.00+ from a local auto parts store). It should be noted that clearing trouble codes will also erase emission monitors (readiness flags). Once trouble codes are cleared (reset), a drive cycle must be performed to complete (set) the emission monitors.

Emission monitors require specific engine operating conditions before a particular emission monitor is initiated. In most cases, the monitors should run during normal vehicle operation. However, due to individual driving requirements, the criteria required to run a monitor may not always be met. By following the Pontiac Vibe drive cycle below all emission monitors will run. The drive cycle must be followed accurately.

Take extra caution when performing the drive cycle on public roadways. Perform the drive cycle at your own risk. If you feel you might not be able to perform the drive cycle safely, or obey all traffic laws, seek the assistance of a smog check repair station which will be able to perform the drive cycle on a dynamometer.

How to Perform a Pontiac Vibe Drive Cycle

The following procedure is designed to complete the OBD-II monitors required to get your Pontiac Vibe to pass the OBD-II Monitors portion of the smog check, also known of the I/M readiness test.

Drive Cycle Recommendations:

A.Most OBD-II monitors will complete more readily using a "steady foot" driving style during cruise or acceleration modes. Operating the throttle in a "smooth" fashion will minimize the time required for monitor completion.

B. Fuel tank level should be between 1/2 and 3/4 fill with 3/4 fill being the most desirable.

C.The Evaporative Monitor can only operate during the first 30 minutes of engine operation. When executing the procedure for this monitor, stay in part throttle mode and drive in a smooth fashion to minimize "fuel slosh".

Drive Cycle Preparation  - 1. Turn key on with the engine off. Cycle key off, then on. Start vehicle WITHOUT returning to Key Off. Idle vehicle for 15 seconds, then drive at 40 MPH until ECT is at least 170°F.

HEGO Monitor - 5. Cruise at 40 MPH for up to 4 minutes.

EVAP Monitor - 6. Cruise at 45 to 65 MPH for 10 minutes (avoid sharp turns and hills) Note: To initiate the monitor your gas tank level must be between 15 and 85%.

Catalyst Monitor - 7. Drive in stop and go traffic conditions. Include five different constant cruise speeds, ranging from 25 to 45 MPH over a 10 minute period.

EGR Monitor - 8. From a stop, accelerate to 45 MPH at 1/2 to 3/4 throttle. Repeat 3 times.

SEC AIR/CCM (Engine) - 9. Bring the vehicle to a stop. Idle with transmission in drive (neutral for M/T) for 2 minutes.

CCM (Trans) - 10. For M/T, accelerate from 0 to 50 MPH, continue to step 11. For A/T, from a stop and in overdrive, moderately accelerate to 50 MPH and cruise for at least 15 seconds. Stop vehicle and repeat without overdrive to 40 MPH cruising for at least 30 seconds. While at 40 MPH, activate overdrive and accelerate to 50 MPH and cruise for at least 15 seconds. Stop for at least 20 seconds and repeat step 10 five times.

Misfire & Fuel Monitors - 11. From a stop, accelerate to 65 MPH. Decelerate at closed throttle until 40 MPH (no brakes). Repeat this 3 times.

Readiness Check - 12. If using a scan tool, access the on-board system readiness (OBD-II monitor status) function on the scan tool. Determine whether all monitors have completed. If not, repeat the drive cycle. If the EVAP monitor is not complete, park the vehicle overnight and begin a new drive cycle after 8 hours (after the engine has completely cooled down).


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