2003 silverado 1500 5.3L gas with a P0420 code, inefficient catalytic bank 1... i have no other codes...what elso can I check , meaning what can i start testing to troubleshoot and repair this

Asked by Jun 07, 2014 at 12:42 PM about the 2003 Chevrolet Silverado 1500 Long Bed 2WD

Question type: Maintenance & Repair

im not burning oil, im not losing any coolant, it runs relativlely strong except at times it
runs a little rough.  what also can I check on ?  could you walk me thru the diagnostic
process to get my trucki back in shape?

2 Answers

75,525

Sounds like you need a new catalytic converter. You can check the downstream oxygen sensor(s) to be sure. Basically what sets this trouble code is when the computer (PCM) "sees" too much fluctuation in the exhaust gases leaving the catalytic converter. Faulty wiring for the downstream oxygen sensor or a bad downstream oxygen sensor can, occasionally trigger this trouble code. But if your Silverado has higher mileage on it I'm willing to bet the catalytic converter is worn out. HTH. -Jim

Po420 Bank 1 and Po430 Bank 2 is your upstream and down stream 02 sensors so just change those and erase code my scanner or battery post take off it will run rough miss some pulling a little while driving and maybe a couple other signs too.

Your Answer

Chevrolet Silverado 1500 Experts

  • #1
    John Carson
    Reputation
    3,020
  • #2
    Rowefast
    Reputation
    2,200
  • #3
    Andrew Olsen
    Reputation
    1,930
View All

Related Models For Sale

Used GMC Sierra 1500
1,120 Great Deals out of 61,769 listings starting at $1,295
Used Ford F-150
3,046 Great Deals out of 230,455 listings starting at $1,300
Used Chevrolet Silverado 2500HD
440 Great Deals out of 31,399 listings starting at $2,500
Used Dodge Ram 1500
324 Great Deals out of 10,738 listings starting at $1,988
Used Toyota Tundra
627 Great Deals out of 36,312 listings starting at $1,500
Used Toyota Tacoma
550 Great Deals out of 41,422 listings starting at $2,500
Used Chevrolet Tahoe
822 Great Deals out of 40,009 listings starting at $1,700
Used Chevrolet Colorado
316 Great Deals out of 42,505 listings starting at $1,299
Used Ford F-250 Super Duty
442 Great Deals out of 47,647 listings starting at $695
Used Chevrolet Camaro
398 Great Deals out of 31,484 listings starting at $3,495
Used GMC Sierra 2500HD
114 Great Deals out of 14,812 listings starting at $3,259
Used Ford Mustang
341 Great Deals out of 42,379 listings starting at $1,488
Used Nissan Titan
324 Great Deals out of 21,857 listings starting at $1,995

Used Cars For Sale

2018 Chevrolet Silverado 1500 For Sale
9 Great Deals out of 83,734 listings starting at $19,263
2017 Chevrolet Silverado 1500 For Sale
253 Great Deals out of 14,511 listings starting at $16,439
2016 Chevrolet Silverado 1500 For Sale
265 Great Deals out of 7,033 listings starting at $16,777
2015 Chevrolet Silverado 1500 For Sale
444 Great Deals out of 11,457 listings starting at $12,999
2014 Chevrolet Silverado 1500 For Sale
457 Great Deals out of 10,491 listings starting at $9,300

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.