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Failed Smog Test

Honda Civic Monitors Not Ready

My Honda civic failed the smog test due to "monitors not ready". I have been told by 3-4 different mechanics just to drive the car around. This has not helped. Before taking the car to get tested I had a oil change and gasket repaired due to small oil leak. What can help get my car's monitor to read?


You will need to drive your Honda Civic for at least 200-300 miles through various driving conditions in order to complete the required Emission Monitors. Sometimes simply driving an extend length of time does not necessary set monitors (or make the monitors complete/ready). Your Honda Civic's engine control unit performs internal self-tests in order to ensure your the engine is running efficiently and not polluting. These self-tests are called Monitors. The entire process of self-testing various emission control systems is called a Drive Cycle. By following the Honda Civic drive cycle below you will be able to get the monitors to run, and if all tests pass, become ready for the smog test. Obey all traffic laws while performing drive cycles. Please perform the drive cycle cautiosly and at your own risk. Use a OBD-II scan tool to check the status of the monitors once you've completed the drive cycle at least once.

How To Perform a Honda Civic Drive Cycle

The following is a Honda Civic OBDII Drive Cycle Pattern.

Cold Start: Begin from Cold Start, and ignition in OFF position for at least 1 hour. ensure your Honda’s fuel tank is between 1/4 and 3/4 full and engine coolant temperature must be below 122°F and within 11°F of the ambient air temperature. Do not leave the key on prior to the cold start or the heated oxygen sensor diagnostic may not run.

Idle Time: Run your Honda Civic’s engine (do not drive) for 2 1/2 minutes with the air conditioner on and rear defroster on. During this period the ECU will be running the Oxygen Sensor Heater self-test, Air Injection System Passive Air test, EVAP Purge "No Flow" test, Misfire Detection.

Acceleration: Turn off the air conditioner and rear defroster and begin driving. As soon as possible apply half throttle until 55mph is reached. The ECU will now run self-tests on the Misfire Detection, Fuel Trim, and EVAP Purge Flow.

Hold Steady: Now hold your vehicle speed steady at 55mph for three minutes. During this time the Oxygen Sensor O2 response, Air Intrusive (AIS System), EGR Flow, Purge Valve, Misfire Detection, and Fuel Trim diagnostics will be performed.

Deceleration: During this step you want to slowly let off the accelerator pedal. Do not brake or shift your Honda in order to slow down. It is important to let the vehicle coast along gradually slowing down to 20 mph. The ECU will once again self-test the EGR System, EVAP Purge System and Long Term Fuel Trims.

Accelerate: Go ahead and accelerate again at 3/4 throttle until 55-60mph is reached. This will perform the same self tests as during the first acceleration step.

Hold Steady: Hold steady speed once again. This time at 55mph for five minutes. During this time, in addition to running the self-tests as during the first HOLD STEADY step, the ECU will perform the catalyst monitor diagnostics. If the catalyst (Catalytic Converter) is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst,or in order to Complete the CAT Monitor.

Decelerate: This will perform the same diagnostics as in the first Deceleration. Remember not to press your Honda’s brake or shift gears during deceleration.

This should complete the drive cycle on your Honda Civic. To ensure all monitors are complete use a scan tool to view the monitors. You may want to complete the drive cycle 2-3 times.

posted by SmogTips Support

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