P0420

2001 GMC SONOMA

95,000 MILES • 4 CYL • 2WD • AUTOMATIC

TALLMAN1781

MEMBER
1 POST
FOLLOW

i have a 2001 gmc sonoma 2wd 2.2 liter and have the P0420 code for catylyst efficiency low bank one.. i have a new cat and rear O2 sensor so what else could be causing this?

Dec 13, 2010 at 1:54 AM

Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.

JACOBANDNICKOLAS

AUTOMOTIVE REPAIR CONTRIBUTOR
110,190 POSTS

Have you checked for vacuum leaks? Have you checked the wiring to the O2 sensor to make sure it isn't damaged or corroded where it pluggs into the O2 sensor?

Let me know.
Joe

Dec 15, 2010 at 4:48 PM