Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P2270: Secondary HO2S (Sensor 2) Circuit Signal Stuck Lean; DTC P2271: Secondary HO2S (Sensor 2) Circuit Signal Stuck Rich
- Turn the ignition switch to ON (II).
- Clear the DTC with the HDS.
- Start the engine. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
- Test-drive under these conditions:
- Monitor the OBD STATUS for DTC P2270 or P2271 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
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 secondary HO2S (Sensor 2) and the PCM. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, Go to step 3 and recheck.
- Turn the ignition switch to LOCK (0).
- Replace the secondary HO2S (Sensor 2) (see Secondary HO2S Replacement ).
- Turn the ignition switch to ON (II).
- Reset the PCM with the HDS.
- Do the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).
- Start the engine. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle.
- Test-drive under these conditions:
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P2270 or P2271 indicated?
YES -Check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM, then Go to step 1.
NO -Go to step 14.
- Monitor the OBD STATUS for DTC P2270 or P2271 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 13, go to the indicated DTC's troubleshooting.
NO -If the screen indicates FAILED, check for poor connections or loose terminals at the secondary HO2S (Sensor 2) and the PCM, then Go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, Go to step 11.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.