Yukon Denali Fuel Trim bank One and Two running too lean?
SES light is on and the pcm codes of P0171 and P0174 popped up on the OBDII. Replaced the MAF sensor, reset the the PCM and drove it. Sure enough the SES light came back on. Tested and the same two codes pop up. Whats next? 2002 GMC Yukon denali
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P0300 is a random miss fire , a vacuum leak can cause this as well as low fuel pressure ! weak fuel pump , clogged fuel filter !
DTC P0171: Fuel Trim System Lean Bank 1
DTC P0174: Fuel Trim System Lean Bank 2 These two codes are saying the PCM - engine computer is see a lean condition .
DTC P0191: Fuel Rail Pressure (FRP) Sensor Performance
The fuel pressure sensor is located on the fuel line. The fuel pressure sensor monitors the fuel pressure in the fuel line. The fuel pump flow control module (FPCM) monitors the voltage signal from the fuel pressure sensor.
You don't say what make , model an year vehicle ! These are for GM vehicles , yours could mean something else . Except the first three , those are genaric codes , same for all makes ! So can't say what this codes are P2097, and P2099 ! Can't mean this P2097 - Post Catalyst Fuel Trim System Too Rich Bank 1
P2099 - Post Catalyst Fuel Trim System Too Rich Bank 2
code po444 is referencing a purge control problem. this could be a bad connection or a problem with the purge solenoid for the evaporative system(EVAP). this is controlled by the PCM to allow fuel vapours to be drawn into the engine and burnt from the gas tank under certain conditions. the p0174 is a lean running condition on bank 2 and p0171 is a lean running condition on bank 1. the lean running conditions could be O2 sensors, lean condition caused by bad fuel pressure, dirty injectors, bad MAF sensor, vacuum leak.
DTC P0171 probable cause:
1. Wire harness problem. Check for correct voltage, opne, short toground, short to voltage
2. Fuel pressure problem. Check pump, regulator, filter and lines
3. Exhaust leaks or restrictions
4. Vacuum hoses. Leaks or incorrect routing
5. Contaminated fuel
6. Sensor improperly installed
DTC P0174 probable cause:
1. Faulty sensor or solenoid
2. Damaged or corroded connector terminal contact
3. Wire harness problem. Check for correct voltage, open, short to ground, short to voltage
4. Control unit software in need of update
5. Faulty PCM or ECM
6. Lean fuel mixture
7. Fuel pressure problem. Check pump, regulator, filter, and lines
P0171 Fuel trim bank one condition Lean (If bank one and two codes set together suspect fuel pressure or MAF sensor. Or O2 sensor defective
P0174Fuel trim bank two condition Lean (same as above or Failed H02S21 Heated O2 sensor Bank 2 sensor 1)
Here we go.... just pulled out our service ticket:
Soooo interesting, I had never looked at these before:
So on 1/10/2005 we took the Vue in, and they did the following:
"CUSTOMER STATES THE SES LIGHT IS ON"
TECH COMM: SES LIGHT IS ON. FOUND FUEL TRIM LEAN CODE P0171 & P0174. RETORQUE INTAKE VACUUM CHAMBER BOLTS AND INSTALL VACUUM CHAMBER SPRINGS PER BULLETIN02/06/01/016A
REPAIR 1: INLET AIR CONTROL VACUUM RESERVOIR - REPLACE
Then, evidently it came back on a week later:
LINE1: "CUSTOMER STATES THE SES LIGHT IS ON"
TECH COMM: SES LIGHT IS ON.
FOUND CODE P0171 FUEL TRIM LEAN B1 CODE P0174
FOUDN MASS AIR FLOW SENSOR FAILED REPLACED MAF SENSOR
code p0128 indicates a mechanical fault ( could be the thermostat stuck open)
code p0174 -system too lean -bank2 ===causes --intake /exhaust leak--fuel pressure/pump--injectors--AIR system--hose connection/s
code po171 refers to system too lean bank 1 same as po174 with the HO2S sensor being the culprit. As to all being related . only by way of the o2 sensors
code p0442 is not connected to the first 3 as it is in a different section of the fuel system
P0171 ; Fuel Trim System Lean (Bank 1)
P0174; Fuel Trim too Lean (Bank 2)
fuel trim is system to modify injector pulse if system go lean it will go rich when the system is too much lean and is max.rich it code
look for 02 sensor bank 1 and 2 data
hope it helps
This is sign of a vacuum leak (possible off of the PCV system). This causes additional air to be introduced into the engine causing the fuel mixture to lean out. With the engine running, shoot short burst of starting fluid around the vacuum lines. When the engine revs briefly, you have found (at least one of) your leaks.