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2018 Silverado

frustrated andy
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frustrated andy Enthusiast

frustrated andy

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I have a 2018 Silverado 5.3 the check engine light stays on ,code 420 and 430 . I have replaced the exhaust (y pipe back) and the sensors , I've replaced the spark plugs and wires light is still on and reading the same codes. Need help with it 

rav3 Senior Enthusiast

rav3

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Posted

Did you ever clear the codes?

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

Those are cat codes, did you actually replace the cats themselves?

 

You typed you replace the y-pipe back, does that mean the y-pipe itself or the cat back?

 

And did you go with OEM or aftermarket?

 

If aftermarket they usually set a check engine light. You can try to space the rear sensors out of the exhaust stream some to not trip the code.

rlcole321 Enthusiast

rlcole321

Posted
Posted

Now did you replace the exhaust parts "Because" of the codes, or for another reason?, your mechanic should be able to read the DataStream to see if the O2's are within their respective ranges, like upstream O2's should fluctuate between .100 to .900 vdc rapidly, and the downstream O2's should stay high about .700 to .900 vdc all the time (with veh at temp.) Did you replace any O2's?  You can buy a fairly good OBDII scanner to read this data at fairly low prices.

frustrated andy Enthusiast

frustrated andy

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The truck has went into a safety mode because of the catalytic converters codes. I've called a Chevrolet garage to come get the junk 😡. 

 

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

Cat codes themselves should never cause reduced engine power, I've never seen that before.  A different issue surely could though.

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