SYSTEM TOO LEAN BANK 1&2

PO 171 Bank 1 too lean
PO 174 Bank 2 too lean
Why ?
The front O2 Sensors need to be replaced at
100,000 miles or sooner, if they have actually failed
They are reading too lean because the system is too
rich & the computer is driving the fuel trim or injector
pulse lean, thus the codes or failed sensors, yes both
Have to check fuel trim with a scan tool
Have to check fuel pressure
Have to check there are no leaking injectors
Have to check for Vacuum Leaks from the intake
all the way to the exhaust converter
Your working a rich condition keeping in mind the system
is driven lean
You look at fuel trim short & long,sort of a past history
of events
May want to look at converter temps also
The converters won't last long if you have or has
a rich condition from fuel or cylinder misfires
Now the spark plugs can't be over 3 years old
& no mifires,get that out of the way before working
the O2 issues

I've come across these codes before. In almost every case there was an air leak in the intake air hose (hose between the engine air filter & the throttle body). Inspect this hose & tubes attached to it. This is especially true when the lean code includes the comment 'at idle'
P2187 - System too lean at idle Bank 1
P0174 - System too lean Bank 2
P2189 - System too lean at idle Bank 2
P2195 = HO2S Signal Biased/Stuck Lean (Bank 1 Sensor 1)
P2270 = HO2S Signal Stuck Lean (Bank 1 Sensor 2)
P2272 = HO2S Signal Stuck Lean (Bank 2 Sensor 2)

P2187 & P2189 = In order to provide the best possible combination of drivability, fuel economy and emission control, the PCM uses a closed loop air/fuel metering system. The PCM monitors the HO2S signal voltage and adjusts fuel delivery based in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The PCM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The PCM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition

PO 171--is an O2 Sensor Code for a Lean Condition
on Bank 1 (right side exhaust)

PO 174 -- is an O2 Sensor Codes for a Lean Condition
on Bank 2 (left side exhaust)

You gave us no vehicle
You gave us no drivability issues or
vehicle history,nothing

If the O2's have 100,000 miles on them,change the (2)
closest to the engine. They are most likely worn out
& the switching times are too slow to control injector
pulse width & thus set a MIL Lamp (OBD2 Fault ) on
your dash

You can learn a lot on the internet if you put OBD2 in your
Search Engine (Internet Explorer,etc)

P2197 - Oxygen Sensor Signal Biased/Stuck Lean Bank 2 Sensor 1
P2187 - System Too Lean At Idle Bank 1
P2177 - System Too Lean Off Idle Bank 1
P2195 - Oxygen Sensor Signal Biased/Stuck Lean Bank 1 Sensor 1
P2179 - System Too Lean Off Idle Bank 2

I am not sure what your Mazda is, but from the sounds of it, both of your Oxygen Sensors are shot. Replace them both, or check for vacuum leaks. It may be a good time to inspect and replace the PCV Valve and PCV Valve hose, too.


I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

code P1128 02 sensor bank 1 lean
code P1129 02 sensor bank 1 lean to limit
code P1133 02 sensor bank 2 lean
code P1134 02 sensor bank 2 lean to limit

fuel system is lean.

Generic OBD II Diagnostic Trouble Codes

DTC CODES P0200 to P0299

P0200....Injector Circuit

P0201....Injector Circuit - Cylinder 1

P0202....Injector Circuit - Cylinder 2

P0203....Injector Circuit - Cylinder 3

P0204....Injector Circuit - Cylinder 4

P0205....Injector Circuit - Cylinder 5

P0206....Injector Circuit - Cylinder 6

P0207....Injector Circuit - Cylinder 7

P0208....Injector Circuit - Cylinder 8

P0209....Injector Circuit - Cylinder 9

P0210....Injector Circuit - Cylinder 1

P0211....Injector Circuit - Cylinder 11

P0212....Injector Circuit - Cylinder 12

P0213....Cold Start Injector 1

P0214....Cold Start Injector 2

P0215....Engine Shutoff Solenoid

P0216....Injector/Injection Timing Control Circuit

P0217....Engine Coolant Over Temperature Condition

P0218....Transmission Fluid Over Temperature Condition

P0219....Engine Over Speed Condition

P0220....Throttle/Pedal Position Sensor/Switch 'B' Circuit

P0157....O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)

P0158....O2 Sensor Circuit High Voltage (Bank 2 Sensor 2)

P0159....O2 Sensor Circuit Slow Response (Bank 2 Sensor 2)

P0160....O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)

P0161....O2 Sensor Heater Circuit (Bank 2 Sensor 2)

P0162....O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)

P0163....O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)

P0164....O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)

P0165....O2 Sensor Circuit Slow Response (Bank 2 Sensor 3)

P0166....O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)

P0167....O2 Sensor Heater Circuit (Bank 2 Sensor 3)

P0168....Fuel Temperature Too High

P0169....Incorrect Fuel Composition

P0170....Fuel Trim (Bank 1)

P0171....System too Lean (Bank 1)

P0172....System too Rich (Bank 1)

P0173....Fuel Trim Malfunction (Bank 2)

P0174....System too Lean (Bank 2)

P0175....System too Rich (Bank 2)

P0176....Fuel Composition Sensor Circuit

P0177....Fuel Composition Sensor Circuit Range/Performance

160....O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 2)

P0161....O2 Sensor Heater Circuit (Bank 2 Sensor 2)

P0162....O2 Sensor Circuit Malfunction (Bank 2 Sensor 3)

P0163....O2 Sensor Circuit Low Voltage (Bank 2 Sensor 3)

P0164....O2 Sensor Circuit High Voltage (Bank 2 Sensor 3)

P0165....O2 Sensor Circuit Slow Response (Bank 2 Sensor 3)

P0166....O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)

P0167....O2 Sensor Heater Circuit (Bank 2 Sensor 3)

P0168....Fuel Temperature Too High

P0169....Incorrect Fuel Composition

P0170....Fuel Trim (Bank 1)

P0171....System too Lean (Bank 1)

P0172....System too Rich (Bank 1)

P0173....Fuel Trim Malfunction (Bank 2)

P0174....System too Lean (Bank 2)

P0175....System too Rich (Bank 2)

P0176....Fuel Composition Sensor Circuit

P0177....Fuel Composition Sensor Circuit Range/Performance

P0178....Fuel Composition Sensor Circuit Low Input

P0179....Fuel Composition Sensor Circuit High Input

P0180....Fuel Temperature Sensor A Circuit

P0181....Fuel Temperature Sensor A Circuit Range/Performance

P0182....Fuel Temperature Sensor A Circuit Low Input

P0183....Fuel Temperature Sensor A Circuit High Input

P0184....Fuel Temperature Sensor A Circuit Intermittent

P0185....Fuel Temperature Sensor B Circuit

P0186....Fuel Temperature Sensor B Circuit Range/Performance

P0187....Fuel Temperature Sensor B Circuit Low Input

P0188....Fuel Temperature Sensor B Circuit High Input

P0189....Fuel Temperature Sensor B Circuit Intermittent

P0190....Fuel Rail Pressure Sensor Circuit

P0191....Fuel Rail Pressure Sensor Circuit Range/Performance

P0192....Fuel Rail Pressure Sensor Circuit Low In put

P0193....Fuel Rail Pressure Sensor Circuit High Input

P0194....Fuel Rail Pressure Sensor Circuit Intermittent

P0195....Engine Oil Temperature Sensor

P0196....Engine Oil Temperature Sensor Range/Performance

This can be caused by a faulty mass air flow sensor

P0171------ system too lean bank#1
Po174------ system too lean bank#2
For these 2 codes, try cleaning the maf sensor (mass air flow), that is mounted in the big black hose that goes from the air filter housing to the throttle plate, if it is dirty, that will cause those 02 sensors to send a signal to the computor to lean the air fuel mixture. If cleaning it doesn't work, the sensors will probably need changing.
P0300---- Random/multiple cylinder misfire
P0316---- Cylinder misfire at start up---- first 100 revolutions.
On those 2 codes, you have to do some testing to find out why there is a misfire.
Possible causes:
dirty/malfunctioning injectors
weak coil pack
fowling spark plugs/wires
Low fuel pressure

I have a van that had a similar problem. Not sure if the rodeo has O rings. That was my problem.