Sorry, no experience with Gen5.
However, looking through my Gen3 service manual, P2A00 is associated with a failing upstream O2 sensor. Maybe check for a faulty connection, burned wire, etc. Of course, you could also just replace it.

DTC P2A00: A/F Sensor (Sensor 1) Range/Performance Problem
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.
1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
4. Test-drive under these conditions:
Engine coolant temperature (ECT SENSOR 1) above 158 F (70 ºC)
Transmission in D position
Vehicle speed at 26 mph (41 km/h) or more, and engine speed at 3,250 rpm or less
Drive with the throttle fully opened for 5 seconds from an engine speed of 1,600 rpm, then slow down with the throttle completely closed.
5. Monitor the OBD STATUS for DTC P2A00 in the DTCs MENU with the HDS.
Does the screen indicate FA/LED? YES-Go to step 6.
NO-If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM. lf the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 3 and recheck.
6. Turn the ignition switch OFF.
7. Replace the A/F sensor (Sensor 1).
8. Turn the ignition switch ON (II).
9. Reset the PCM with the HDS.
10. Do the PCM idle learn procedure.
11. Test-drive under these conditions:
Engine coolant temperature (ECT SENSOR 1) above 158 F (70 ºC)
Transmission in D position
Vehicle speed at 26 mph (41 km/h) or more, and engine speed at 3,250 rpm or less
Drive with the throttle fully opened for 5 seconds from an engine speed of 1,600 rpm, then slow down with the throttle completely closed.
12. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P2AOO indicated? YES-Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM, then go to step 1.

 

Thanks very much for the reply. I guess I am concerned about kicking the can down the road and if the P2A00 is caused by bad fuel injectors. And since I have 3 months left on the 12 month engine warranty I am wondering if I should just have the dealer look at it. But I really try to avoid going to the dealer if possible.

 

Absolutely take it to the dealer to look at it. Why wouldn't you?

 

I may just take it to the dealer anyway since we have an unrelated issue with the air conditioning no longer working (blowing warm air). I have read of an extended warranty on that and am hopeful that can get covered in some way. Crossing my fingers

 

Hello All. We had the O2 sensor replaced and it ran fine for about 4 days and all the lights are back. The check engine is NOT on and the O2 sensor code (P2A00) is no longer there but all the other lights came on again. Checked battery again and it seems fine. There are no P0172 indicating fuel injectors

Next step is to take it to Honda dealer.

I know the battery checked out fine but would there be any wisdom in replacing the battery?