I need to know what part of the emission system is setting a code. Also, if you purchased it from a dealer and it won't pass inspection, you need to check your state's laws for such things. Here in PA, if it is sold, it has to be inspected and the purchaser needs to be made aware of any issues, and this would be one.

Answered by Jacobandnickolas (expert)
57,475 answers provided

Fault codes : po 171 system too lean bank1. Po174 too lean bank 2 Functional check fail

Response from Apache14142
1 question asked

Below is an explanation of the problem and possible causes.

DTC P0171 OR P0172: FUEL INJECTION SYSTEM FUNCTION (RIGHT OR LEFT BANK)

DTC Confirmation Test

Malfunction is detected when mixture ratio compensation amount is too large (mixture is too lean or too rich).

Possible causes are:

Intake air leaks.
Defective front HO2S.
Defective injectors.
Exhaust leaks.
Fuel pressure incorrect.
Lack of fuel.
Defective MAF sensor.

Answered by KHLow2008 (expert)
40,318 answers provided