OBD Monitors will ready and then unready
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Joined: Mar 2019
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From: California
OBD Monitors will ready and then unready
My RX-8 has to get smogged this week in California. As the title states the car’s obd monitors will show as complete and then I’ll drive it for a bit and they’ll reset again. There is no CEL. All the monitors have shown complete at some point in time except the EVAP so I know the sensors must be working. Could a weak battery be causing it reset every so often? Right now The Cat, O2, EVAP, and secondary air monitors are incomplete. I’ve been doing drive cycle over and over and I can’t seem to keep all the monitors complete.
What am I doing here?
Joined: Mar 2006
Posts: 3,606
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From: 2017 Miata RF Launch Edition
How weak is your battery?
I've noticed that a borderline battery can just barely have enough oomph to start but the voltage drop is so large that the ECU loses its stored values (fuel trims, pcodes, etc).
This only happens to me when I try to use my tiny LiFePO4 battery and it's below 40°F (lithiums don't like cold) but it's possible that it could be happening with a weak OEM battery on a cold morning.
I've noticed that a borderline battery can just barely have enough oomph to start but the voltage drop is so large that the ECU loses its stored values (fuel trims, pcodes, etc).
This only happens to me when I try to use my tiny LiFePO4 battery and it's below 40°F (lithiums don't like cold) but it's possible that it could be happening with a weak OEM battery on a cold morning.
Thread Starter
New Member
Joined: Mar 2019
Posts: 3
Likes: 0
From: California
How weak is your battery?
I've noticed that a borderline battery can just barely have enough oomph to start but the voltage drop is so large that the ECU loses its stored values (fuel trims, pcodes, etc).
This only happens to me when I try to use my tiny LiFePO4 battery and it's below 40°F (lithiums don't like cold) but it's possible that it could be happening with a weak OEM battery on a cold morning.
I've noticed that a borderline battery can just barely have enough oomph to start but the voltage drop is so large that the ECU loses its stored values (fuel trims, pcodes, etc).
This only happens to me when I try to use my tiny LiFePO4 battery and it's below 40°F (lithiums don't like cold) but it's possible that it could be happening with a weak OEM battery on a cold morning.
Thread Starter
New Member
Joined: Mar 2019
Posts: 3
Likes: 0
From: California
I disconnected the battery for 15 minutes and the monitors readied up quickly after a couple drives. I don’t know what caused it but maybe the computer got glitches where tests wouldn’t run and needed to be reset
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