Code 21 and 28 sc400
#1
3rd Gear
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1993 SC400, with 130,000 miles. Only modification is a cat back x pipe with no mufflers. I’ve been getting code 21, and 28. When you first turn the car on no code. The CEL comes on after about 3-10 minutes of driving. I’ve now replaced my o2 sensors with 2 new Bosch upstream o2 sensors. I’m still receiving codes 21 and 28. These are the only codes. Is there anyway I have a pre cat exhaust leak? Or could something else be causing an issue? I know some say it could be the ecu, I am trying to eliminate all other options. Thanks in advance for any help!
#2
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Check to make sure your wiring hasn't been damaged. I think these ECUs are more with idling issues and AC problems.. I'd check the wiring going to the ECU to ensure they weren't modified previously.
#3
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Here's another earlier thread that may help you as well. You may be right with the ECU, but I'd check wiring first as previously stated.
https://www.clublexus.com/forums/per...-and-28-a.html
https://www.clublexus.com/forums/per...-and-28-a.html
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mre2000
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02-03-13 06:21 PM