Monitors not resetting

DAZ3291

MEMBER
2007 HYUNDAI SONATA
2.4L
4 CYL
2WD
AUTOMATIC
160,000 MILES

Failed inspection because of 02 and catalyst monitors not ready. Drove care four hundred miles, from New York to Maryland and back, still not ready. Just found out there is a leak in the flex pipe after the catalytic converter. Could this be the reason for it not ready?

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
43,054 POSTS

Yes that can cause it. When you drove it four hundred miles did you let the engine cool completely at least twice? Also the monitors will not set in open loop which can be caused by a stuck open thermostat which there should be a code for. Here is a guide to run the codes to see:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.

Cheers, Ken

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Monday, November 12th, 2018 AT 11:34 AM

DAZ3291

MEMBER
3 POSTS

Okay, so I drove to Jersey and stopped for maybe thirty minutes then continued straight to Maryland. Next couple of days I drove around in Maryland most of the day, stop and go traffic and time shopping then then back to New York stopping in Jersey again for food. No check engine and still did not run.

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Monday, November 12th, 2018 AT 2:11 PM

KEN L

MASTER CERTIFIED MECHANIC
43,054 POSTS

I would run the codes anyway you could have a pending code which can be the thermostat stuck open which will cause the monitors to not reset. Please run the codes. Sometimes it can take many engine run cycles to set the monitors.

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Tuesday, November 13th, 2018 AT 10:30 AM

DAZ3291

MEMBER
3 POSTS

Yea, I check for codes every time I do a drive cycle. No codes.

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Tuesday, November 13th, 2018 AT 4:40 PM

KEN L

MASTER CERTIFIED MECHANIC
43,054 POSTS

I am wondering if we have a fuse out which causes the PCM to constantly reset. Here is the engine wiring diagrams that show the fuses that run the system and a guide to help you check for power with the fuse locations as well:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below). Please let us know what happens.

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