Greetings,

I have a sweet 2004 Lightning that sits too much. It has 18,000 miles, I just put a Flowmaster muffler on but stock otherwise.

I thought the gas was stale - ran it down - fresh gas still throws Service engine soon during second run. (after battery disconnect)

I found Stewart's instructions fo downloading codes: First reading, what I believe DTC was none - the letters weren't exactly DTC

update, So far, knock on wood,, I think the good gas fixed the service light. I've had the truck out 3 times and still no faults of lights. sorry for jumping the gun

 

New day, light came back after about 20 miles. It was going off under 5 miles. Consistently.

When I try to view the codes, I can't get anything but trip miles or odometer.

Push button, turn key, odometer illuminates, release button - it goes to trip or miles.

push button insert key, turn to run, release button early, before, during or after - same thing straight to miles or trip.

start truck, run, turn off. Push button, turn key to run - same thing.

last code reading at Auto Zone was both banks lean, O2 sensors.

 

I've found the on-board diagnostic check to be less than reliable. Many times I've had codes, read them with all three different code readers I own (Predator, SCT, and AE), but not had anything show up through the built in DTC check.

First thought since regarding your lean code, since it sits for long periods, is vacuum leak from hoses that have become compromised through age.

Stewart

 

Not as much fun troubleshooting as driving it.

Is it safe to assume the leak would be in front of the O2 sensor? (sensors)

Swapping sensors would not be your first choice for problem solving?

Thank you for stopping by.

 

The "built-in DTC check" isn't what you think it is. It is restricted only to those systems that communicate through the cluster, it does NOT report anything related to the OBDII system. That level of functionality requires a scan tool talking directly to the PCM.

The "built-in DTC check" is properly called the HEC DTM (Hybrid Electronics Cluster Dealer Test Mode).

 

What they said ^^^^^

You should use an OBD2 reader to pull these codes.

 

My handy AutoEnginuity reader gave me the following results:


P0171 System Too Lean Bank 1
P0174 System Too Lean Bank 2

 

Lean on two banks? First thing I'd check is fuel pressure.

 

More than 90% of the time, that code pair is due to a vacuum leak in the intake tract. The rest of the time, it's spread across contaminated/defective MAF sensors, weak fuel pumps, etc.

You really have to pull the freeze frame data to get a better understanding of the operating conditions when the code was posted in order to diagnose. For example, the conditions for that code pair generation by a vacuum leak vs. a weak pump are markedly different.

Oh, and it is NOT the O2 sensors.

 

Thanks for the tip ProjectSHO89.
Winter really messes with toy time, I'm still here, I did find the double set of service manuals and the electrical volume, for Heritage trucks, should be here before the weather warms lol.

 

New Air filter, no help. New fuel filter, no help.
Checked and cleaned MAF sensor, FIXED IT.