With a scanner, check to see what the % of alcohol in the fuel. should be about 3-5 percent. I have seen over 30% on some and it will effect the o2 sensors.

 

When you replace the oxygen sensors on your vehicle, you should take a few steps to ensure that the sensors function correctly and that the vehicle's computer recognizes them. Here's a step-by-step guide to help you address the issue:

1. Reset the Check Engine Light (CEL): If you haven't already, clear the Diagnostic Trouble Codes (DTCs) using a code scanner. After clearing the codes, drive the vehicle for a few days to see if the CEL comes back on. If it does, recheck the codes.
   
2. Perform a Drive Cycle: After clearing the codes, complete the drive cycle. A drive cycle is a specific series of start-up, driving, and shut-down operations the vehicle's computer uses to check all emission-related systems. This can help reset and calibrate the oxygen sensors.
   
3. Check for Wiring Issues: Ensure all the oxygen sensor connectors are correctly connected. Inspect the wiring for any damage or breaks. Even if the oxygen sensors are new, if they're not receiving the correct voltage, or if the signal isn't getting back to the computer because of a wiring issue, you'll get a code.
   
4. Inspect the Fuses: Check the vehicle's fuse panel for any blown fuses related to the oxygen sensors or the engine control module (ECM).
   
5. Check the Sensors: Just because the oxygen sensors are new doesn't mean they're not defective. Rarely, a new sensor might be faulty out of the box. If you can access a multimeter or scan tool, you can test the sensors to ensure they function correctly.
   
6. Battery Disconnect: Although you didn't disconnect the battery initially, doing so now can help. Disconnect the negative terminal of the battery for 15-20 minutes. This will reset the ECM and might help it recognize the new sensors. Remember that by doing this, you'll reset all memory settings in the vehicle, including radio presets and clock settings.
   
7. Update the ECM: Sometimes, older vehicles may benefit from an ECM software update. Check with your local dealership or a trusted mechanic to see if there's a software update available for your vehicle's ECM.
   
8. Double-check for Other Issues: Oxygen sensor codes can sometimes be triggered by other problems, such as vacuum leaks, exhaust leaks, or issues with the fuel system. Ensure there aren't any other underlying issues that might be causing the DTCs.
   
9. Seek Professional Help: If you've tried all of the above and the codes persist, it might be time to consult a professional mechanic. They can use specialized diagnostic tools to pinpoint the issue and offer solutions.
   

Remember, while it's essential to clear any DTCs before a state inspection, ensuring your vehicle is running efficiently and not emitting pollutants beyond allowable levels is equally crucial. The oxygen sensors play a critical role in monitoring and managing emissions.

 

i assume since this person "just got an ODBII scanner", he has not yet erased codes or didn't buy OEM sensors (got sensors off amazon.com says "fits this vehicle" and they didn't)

please confirm how you obtained these 4 sensors. the dealer or ebay?

please confirm if the "vendor" required you to "re-wire" the sensors due to incompatible connectors