DTC Code on Nevada Emission (SMOG) Report

[franklasvegas]

Hello all:

Wondering if anyone can tell me exactly what this means:

P0171 - Fuel Injection System Too Lean (Bank 1)

It appears on the SMOG report I had done today as a DTC code. The car (2000 Infiniti I30 STD) pass the test - no problems with that - just curious what it means.

Thanks!

Frank in Las Vegas

[elwesso]

Hmmm, my guess its just one of those codes that doesnt relaly matter, as long as the CEL isnt staying on and your o2 sensors are good.

[DAEDALUS]

The code is saying that the bank is reading too little fuel. Could be from a clogged or faulty injector, low fuel pressure (that would probably trigger both banks though), sluggish O2 giving a bad reading. If the code is valid and/or if the ECU is trying to compensate for the error, such as run too rich, then the vehicle is not running as well as it should be. Its peformance and/or mileage could be suffering. No smog check will ever fail you for emitting too few hydrocarbons, but that would be a problem. How were the NOx numbers relative to the averages?

Maybe when Wes has some free time he can list for us which error codes don't really matter.

[elwesso]

All im saying is it might have been a history code where its basically telling you "Long long ago, in a galaxy far far away, this car ran a little bit lean"..... Its not that it doesnt matter, personally id clear the code and see if it comes back....

[franklasvegas]

Thanks for your input.

Funny - the car runs so smooth - there are times I actually wonder if it is on. On a recent highway trip - 28 & 29 MPG and around town 20 & 21 MPG.

Upon acceleration (at times - not always) some slight engine knocking.

Just one of those weird code reports I would think at this point.

Frank in Las Vegas

[DAEDALUS]

Upon acceleration (at times - not always) some slight engine knocking.

May or may not be related, but running too lean is a cause of engine knock. Knocking can be very destructive. If it's only happening in one bank at least the list of suspects is pretty limited.