What this code means
P2270 can indicate that the secondary oxygen sensor signal stays lean while its heater receives power.
What the vehicle may do
- The sensor output can stay low while its heater is powered.
Possible fault areas
- The secondary HO2S (Sensor 2) or its signal circuit may be involved.
Diagnostic path
What P2270 means
On this 2025 Honda Accord 1.5, P2270 means Secondary Heated Oxygen Sensor (Secondary HO2S) (Sensor 2) Circuit Signal Stuck Lean. We will call it the secondary HO2S from here. The PCM stores this code when the sensor output voltage stays below a specified value while its heater receives power. The possible fault area is the sensor or its signal circuit. Here is what this code tells us. The sensor output can stay low while its heater is powered. Here are the main areas to check. The secondary HO2S (Sensor 2) or its signal circuit may be involved.
The PCM's decision combines two conditions: heater power is applied, and the secondary HO2S output voltage is below the specified value. Heater power alone is not the abnormal result; the low sensor output under that condition is what the PCM identifies.
Before troubleshooting
Before you troubleshoot, review How to Troubleshoot.
Listed sensor work
The listed work item for the Secondary HO2S (Sensor 2) is replacement of that sensor.
Confirmation Procedure: warm-up
Here is the separate Confirmation Procedure. It begins by starting the engine. With no load and the transmission in P or N, hold the engine speed at 3,000 rpm. Keep it there until the radiator fan comes on. Then let the engine idle for 2 minutes.
Confirmation Procedure: drive conditions
The diagnostic scanner (HDS) lists ECT Sensor 1 and Engine Speed under PGM-FI > Data List. Next, test-drive the vehicle with ECT Sensor 1 above 158 degrees Fahrenheit (70 degrees Celsius) and the transmission in D. Keep Engine Speed between 1,500 and 3,000 rpm. Drive under these conditions for 30 seconds or more.
The 30-second minimum applies to driving with all the listed conditions together: ECT Sensor 1 above 158 °F (70 °C), the transmission in D, and Engine Speed between 1,500 and 3,000 rpm. The earlier no-load warm-up in P or N is a separate part of the Confirmation Procedure, not a substitute for this driving period.
Monitor the code status
Then use the scanner to monitor OBD STATUS (PGM-FI) for DTC P2270.
More diagnostic steps
For more diagnostic steps, visit stepdiagnostics.com.
Final check
P2270 can reflect low secondary HO2S output voltage while the sensor heater receives power.
For more guided automotive diagnostics, visit STEP Diagnostics.
