I have a 2010 Honda Accord, V6, with fault code P0325. That is a Knock sensor 1 code. But, as soon as the CEL lit, the ECO mode was Not operational. Last year, I had fault code P3400 Valve Pause System stuck OFF. Honda Tech bulletin said to check engine oil. Since the ECO mode was Not operational this time, I stopped and checked and the engine Oil was low, just at the tip of the dipstick. My question is: Will the P0325 code now present (Note: this is the only code, no others shown) affect the ECO system like the previous fault code did? I am confused. I did add a qt of oil to bring the level up to 1/2 on the dipstick.

 

The PCM may disable the eco mode if it sets a P0325. You'd almost need a scanner to see if any systems are disabled.

Since you have the P0325, you should start by troubleshooting the code. The code can be set by a bad knock sensor, faulty wiring to the sensor, or the PCM. At minimum, unplug the kock sensor and look for any corrosion in the connector. Also look for signs of damage to the wire harness nearby.