I recently bought a used 2021 zforce trail 800 that only has 130 miles on it, because it ran terrible.  Someone had been digging around trying to figure out what the problem was, and I believe the owner said that he had replaced a fuel injector with no luck...

So I dragged it home, and it was blinking a check engine light while running. With the key on/engine off, It blinked out several codes about injectors, 02 sensors, speed sensor... So I started looking around and found that a mouse had chewed through the wiring on the 02 sensor closest to the seats. I fixed the wiring, fired it up, and there is no check engine light at all while its running, and it runs good now....

But, if I have key on/engine off, it still blinks out 9 different codes
0201
0202
0352
0131
0174
0138
0037
0500

But as soon as you start the engine, no check engine light at all.

Are these historic codes that just somehow need to be cleared? Or do I still have an issue that I need to track down?
I took it out on trails for a few hours, and it performed great, no check engine light at all while the engine is running. It is only blinking out the codes with key on/engine off.

Any help is appreciated!

[2015 Z Force 800 53/Trail EPS]

It may be that while the engine isn't running the system voltage is low enough that errors show up and when running the charging system takes the voltage up enough that the errors stop. Test the battery voltage while not running or...put a battery charger on it and turn the key on. The MIL light should come on solid while not running then go off while running and not blink codes. Just a theory to check.  Load test the battery to see if it needs replaced. If OE it's likely it's gone. Oh, and if there was rodent damage one place...it's likely there's another...and probably up high by the ECM. Take a close look..everywhere.

Thanks for the reply. I have all the plastics off that are hiding most of the wiring harness, and the front trunk bucket out so I can see the ECU and wiring. I have looked it over really good and cant see any more damage. I removed both of the chassis ground bolts, and cleaned the wiring connections (were already in great shape) and then tightened it all back up.

Good idea with low battery voltage with the engine off. I will check to see what the voltage is with key on and not running. I will put a charger on it, and turn the key on and see if it still blinks all the codes.

Thanks for the help!

[2015 Z Force 800 53/Trail EPS]

Interestingly enough is that I do not find all the codes you list in the 2018 + fault code listing as shown below but some. Others, not all, are listed on the 15-17 fault code listings. Overall there is enough that makes me feel like there is a system-wide problem..such as a voltage...or a grounding problem somewhere.

That's what I was thinking as well about the grounds. I checked as much of the harness as I could see from the engine back up to the ECU. I cleaned both of the chassis ground locations. I just checked key on/engine off battery voltage, its at 12.39. That should not be causing any issues.

Once it starts, there is no check engine light. Do historic codes remove themselves from the ECU, or does a dealer have to reset it to clear them?

[2015 Z Force 800 53/Trail EPS]

Believe it or not, 12.3 volts is a problem. Static on a good battery should be at or above 12.6. Codes historically on these are not saved or need cleared. They are there until the problem is remedied. Load test that battery. What does it show for voltage running? 

Believe it or not, 12.3 volts is a problem. Static on a good battery should be at or above 12.6. Codes historically on these are not saved or need cleared. They are there until the problem is remedied. Load test that battery. What does it show for voltage running?

That's good to know. I will try it again this evening with a charger on it with key on/engine off, and see if that makes it quit blinking codes. And then check the voltage with it running and report back.

Thanks for the help!

With battery voltage at 13.0v, it still blinks the codes with the key on/engine off.

Is there a possibility that when the mouse chewed the 02 sensor wires, that 2 of the wires could have touched each other and burnt a ground trace inside the ECU? I keep leaning towards a ground issue since there are soooo many codes.

[2015 Z Force 800 53/Trail EPS]

With battery voltage at 13.0v, it still blinks the codes with the key on/engine off.

Is there a possibility that when the mouse chewed the 02 sensor wires, that 2 of the wires could have touched each other and burnt a ground trace inside the ECU? I keep leaning towards a ground issue since there are soooo many codes.

It's possible I guess. Not sure how one would test for that other then try another ECM. So many codes means something system-related like a wiring problem or something with the ECM. Have you tried disconnecting the battery for a few minutes just to be sure nothing is in memory?

Finally got it figured out and fixed. There is one more ground wire, that grounds to the mounting bolt of the ECU. Loosened it up, and tightened it back down, and no more issues. Must have just had a little corrosion on the bolts loop wire connection.

Thank you all for the help!!

[2015 Z Force 800 53/Trail EPS]

Finally got it figured out and fixed. There is one more ground wire, that grounds to the mounting bolt of the ECU. Loosened it up, and tightened it back down, and no more issues. Must have just had a little corrosion on the bolts loop wire connection.

Thank you all for the help!!

Good...glad you found it. Happy trails!