I have a 1992 Toyota pickup 4x4 4 cylinder. The computer set code 21 which is the oxygen sensor. I replaced the oxygen sensor and disconnected the battery to clear the code. I reconnected the battery and the check engine light came back on when I turned the switch on. I checked and the computer code was 21. I tried clearing the code by disconnecting the battery multiple times, but each time I turn the switch on the check engine light comes back on with code 21.

SOURCE: check engine light

see if throttle body need to be cleaned

SOURCE: The check engine light keeps coming on for a 1998 Toyota Avalon.

Did you buy the universal replacement sensor where you use the plug off of the old sensor and the splice kit? If so, that is most likely the issue. Had the same problem on a 2003 Avalon. Bought the ones with the plug and codes cleared. ps. Check Amazon.com, lots less expensive.

Sean Wright

• 2045 Answers
• Posted on Nov 13, 2009

SOURCE: how do I find out if my ecu is bad. I keep getting

Make sure the check engine light was cleared after you replaced the o2 sensor....if the codes were not cleared then it will come on forever even if thetre is no problem


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SOURCE: i have a toyota rav4 2003 management light came on

The upper sensors are air fuel sensors and the lower ones are o2 sensors. you cant mix these up. Assuming you did everything right and still coding then either the new sensor b1s2 is bad or the wirng(power and ground need to be checked. A scan tool can be used to look at the performance of the sensors too. Sometimes the codes just point to the area of the problem and changing the part isn't the answer.

SOURCE: VSC Trac off/ VSC Trac

how do I determine which oxygen sensor is bad on my 2003 forerunner ? the check engine light is on and also the vsc trac