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O-2 Heater Monitor Won't Set.

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This topic contains 6 replies, has 3 voices, and was last updated by David Erhahon David Erhahon 2 months, 4 weeks ago.

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    Topic
  • #986762
    Lady DI
    Lady DI
    Participant

    04 Hyundai Santa Fe 2.7l, I been trying to get the O2 heater monitor to set for weeks now no luck. On weekends I take 2 hour trips still no luck. No CEL and in July I changed the battery. I live in CA and all monitors must set or no registration renewal which is in Jan 2021. I tried to do my due diligence with researching the problem, very little information available that I found for this vehicle. Most said changing the 4 O-2 sensors did not help them. Can anyone help me as this car runs great low mileage and is always garaged.

    • This topic was modified 3 months ago by Lady DI Lady DI.
Viewing 6 replies - 1 through 6 (of 6 total)
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  • #986765
    Nightflyr *
    Richard Kirshy
    Participant

    Hyundai’s have really odd drive cycles. A drive cycle is a structured test drive where the computer tests all the of the Emission Components and Systems in a step by step process.
    Here are 2 methods for completing the drive cycle:
    To perform an OBDII Driving cycle do the following: 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. 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. 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. 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. 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. Accelerate. Accelerate at 3/4 throttle until 88-96 km/hr (55-60mph). This will perform the same diagnostics as in step 3. 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. Decelerate. This will perform the same diagnostics as in step 5. Again, don’t press the clutch or brakes or shift gears.

    The following is a description of the Hyundai Sonata Drive Cycle. Prior to beginning the drive cycle ensure your Sonata has at least 1/4 to 3/4 tank of gas. An empty or full gas tank will not allow the EVAP monitor to run. Also begin the drive cycle from a cold start; best achieved by leaving your vehicle sitting overnight.

    Hyundai Sonata Drive Cycle

    STEP 1:
    • Make sure check engine light is not on and that there are no stored trouble codes in the computer. Use a scan tool to check for OBD II trouble codes. Any faults founds need to be repaired first.
    • Start the engine. Keep the vehicle in Park.
    • Idle the engine for 1 1/2 minutes.

    STEP 2: (Steady State Driving – Part 1)
    • Accelerate within 15 seconds to 50-55 mph (using 1/4 to 3/4 throttle) and keep this speed steady for 2 to 3 minutes.
    • Decelerate to 0 mph without braking.
    • Idle engine then idle in Drive for 1 to 2 minutes.

    STEP 3: (Steady State Driving – Part 2)
    • Accelerate within 15 seconds to 50-55 mph (using 1/4 to 3/4 throttle) and keep this speed steady for 10 to 20 minutes.
    • Decelerate to 0 mph without braking.
    • Idle engine then idle in Drive for 1 to 2 minutes.

    STEP 4: (Engine Stop)
    • The drive cycle is completed.
    • Turn off the engine (key in the OFF position).

    If all other emissions systems are functioning properly, completing the drive cycle above should set or make ready (complete) your Hyundai Sonata’s emission monitors. If the emission monitors are still not complete then check for any trouble codes and whether the check engine light is on or not. If faults are found make the appropriate repairs and conduct the drive cycle twice again. Take extreme caution when performing drive cycles on public roadways. Perform the procedure at your own risk.

    #986769
    Lady DI
    Lady DI
    Participant

    Can the O-2 heater “circuit” be tested with a quality scanner. I want to make sure there is no electrical issue. Again no CEL present.

    #986770
    Nightflyr *
    Richard Kirshy
    Participant

    This should help:

    #986801
    David Erhahon
    David Erhahon
    Participant

    On my 05 accord, the heater monitor sets even while idling. I don’t have to drive anywhere. It should be among the first things to set.
    Most such O2 heater issues are usually due to electrical problems. Either faulty wiring or faulty heater in the sensor.

    You will need a multimeter and your Hyundai wiring diagram to check it.

    #986802
    Lady DI
    Lady DI
    Participant

    David,
    Some of the things you mentioned would trigger a check engine light ,correct? Like a faulty O-2 heater for example, or even faulty wiring. I do not have a CEL. Yesterday I disconnected the battery (a computer reboot) overnight. There is no way to complete the drive cycle where I live. So I’ll start the weekend 2 hours again to see what happens.

    #986803
    David Erhahon
    David Erhahon
    Participant

    Yes, I would expect so.
    Nice idea rebooting the computer.

    Ok

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