i just had a flash done to my computer to try and ready a catalyst and o2 monitor for inspection but even after the download it still reads not ready... do i need to do a cold start for the monitor to re program??
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2006 Hyundai Tiburon Question: do i need to do a cold start for an o2 sensor and catalyst monitor to read ready
pushrod October 21, 2013, 15:17Master
Yes you do.
Answer #2Rojo1 October 21, 2013, 21:32Technician
You will likely need more than a cold start. There is a certain specific drive cycle required to run the monitors. For some reason, most techs don't do this but it will actually verify the repair. Here are the steps in case you want to try it yourself.
1. Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 122°F and within 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 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 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 20 mph. During this time the EGR, Purge and Fuel Trim diagnostics will be performed.
6. Accelerate. Accelerate at 3/4 throttle until 55- 60mph. This will perform the same diagnostics as in step 3.
7. Hold Steady Speed. Hold a steady speed of 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 drive 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.
If this sounds like something you don't want to try, just drive the car normally for a couple days and the monitors should run on their own. Just make sure you drive it in town as well as on the highway.