Banks 1 and 2 Running Lean
#1
Banks 1 and 2 Running Lean
My SES light came on a few weeks ago and has stayed on until the codes were cleared earlier this evening. I had trouble codes present earlier this summer, but before I could pull the codes, a new tank of fuel turned the light off. I figured it was just an emissions problem and shrugged it off.
Tonight I pulled three codes as follows:
P-0420: Catalyst below threshold
P-0171: Bank 1 lean
P-0174: Bank 2 lean
I am thinking that the oxygen sensors need to be replaced on both banks. I believe there are four on my '99 4.6 Supercab; two downstream in the cats and two upstream at the headers.
I realize that this could also be caused by a weak fuel pump, but I have not had problems starting or accelerating. I also know that leaky vacuum hoses could be the culprit. I cleaned the MAF in late May or Early June. Fuel filter was replaced in March (7,000 miles ago).
I am lead to believe the 02 sensors are the culprit because of the P-0420 code.
Thoughts?
Tonight I pulled three codes as follows:
P-0420: Catalyst below threshold
P-0171: Bank 1 lean
P-0174: Bank 2 lean
I am thinking that the oxygen sensors need to be replaced on both banks. I believe there are four on my '99 4.6 Supercab; two downstream in the cats and two upstream at the headers.
I realize that this could also be caused by a weak fuel pump, but I have not had problems starting or accelerating. I also know that leaky vacuum hoses could be the culprit. I cleaned the MAF in late May or Early June. Fuel filter was replaced in March (7,000 miles ago).
I am lead to believe the 02 sensors are the culprit because of the P-0420 code.
Thoughts?
Last edited by defconfive; 09-29-2008 at 08:52 PM. Reason: Added additional details.
#6