P0138
https://static.nhtsa.gov/odi/tsbs/2013/MC-10132202-9999.pdf
1. Check all DTCs.
Are DTC(s) other than P0138 or P0158 present?
• YES —
• P2195 and/or P2197 DTC also present: Go to step 3.
• P0606 DTC also present: Go to step 4.
• NO — Go to step 2.
2. Check the A/F and O2 sensor values for the appropriate bank DTC Freeze Frame Data (FFD).
Is the AFS Voltage B#S1 = 3.35~3.70V AND the O2S B#S2 = 0.70∼0.90V?
• YES — Replace the appropriate bank Air Fuel Ratio Sensor ONLY (NOT O2 Sensor) to
correct the P0138 or P0158 DTC condition.
• NO — Inspect the O2 B#S2 circuit for open, short, or high resistance. If no trouble is found,
refer to TIS, applicable model and model year Repair Manual for P0138/P0158 diagnosis:
3. Inspect Air Fuel Ratio Sensor for the appropriate bank.
Does the Air Fuel Ratio Sensor have an open or short on the A1A+ or A1A– wires?
• YES — Repair the harness and revaluate the Air Fuel Ratio Sensor operation. Confirm
the previous DTC(s) do not reset.
• NO — Replace the applicable bank Air Fuel Ratio Sensor ONLY to correct the P2195/P0138
or P2197/P0158 DTC condition. Test drive the vehicle to confirm none of the previous
DTC(s) reset.
4. Inspect Oxygen Sensor 2 Freeze Frame Data (FFD) values.
Is the O2S B#S2 voltage more than 1.10v and/or the O2S Impedance B#S2 more than 300 ohms
when engine is at normal operating temperature?
• YES — Inspect O2 B#S2 circuit for open, short, or high resistance. If no harness issues are found, replace the appropriate bank O2 Sensor ONLY to correct the P0606 DTC.
• NO — Follow the Repair Manual diagnostic procedure for P0138/P0158 DTC:
If the MIL “ON” condition continues to occur after this procedure, refer to the Repair Manual for further diagnostic procedures and specifications.
P0138
https://share.qclt.com/丰田Toyota%20RAV4%20Repair%20Manual/2AZ-FE%20Engine%20Control%20System/SFI%20System/0050028.pdf
P0138
• High voltage (short):
During active air-fuel ratio control, following conditions (a)
and (b) met for certain period of time (2 trip detection
logic):
(a) HO2 sensor voltage output more than 0.59 V
(b) Target air-fuel ratio lean
• Extremely high voltage (short):
HO2 sensor voltage output exceeds 1.2 V for more
than 10 seconds (2 trip detection logic)
• Short in HO2 sensor (sensor 2) circuit
• HO2 sensor (sensor 2)
• ECM internal circuit malfunction
https://www.cim.mcgill.ca/~cprahacs/gtcs/DTC_Codes.pdf
Code P0138 Toyota Possible Causes Faulty Oxygen Sensor Bank 1 Sensor 2 Oxygen Sensor Bank 1 Sensor 2 harness is open or shorted Oxygen Sensor Bank 1 Sensor 2 circuit poor electrical connection Gas leak from exhaust system
How do I Fix the Code P0138 Toyota? Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
Read more: https://www.autocodes.com/p0138_toyota.html
Code P0138 Toyota Tech Notes Replacing the Oxygen Sensor Bank 1 Sensor 2 (Rear Oxygen Sensor Bank 1 or Downstream Oxygen Sensor Bank 1) usually takes care of the problem. There is a Factory Service Bulletin for the following Toyota models: 2005–2007 Toyota Avalon 2007–2008 Toyota Camry 2005-2007 Toyota Avalon, 2007-2008 Toyota Camry Factory Service Bulletin OBDII Code P0138
What Does the P0138 Toyota Code Mean?
In order to obtain a high purification rate of the Carbon Monoxide (CO), Hydrocarbon (HC), and Nitrogen Oxide (NOx) components in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used.
For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel level.
For the purpose of helping the Engine Control Module (ECM) to deliver accurate air-fuel ratio control, a heated oxygen sensor is used.
The heated oxygen sensor is located behind the TWC and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).
When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high. The heated oxygen sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e. less than 0.45 V).
Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration in the exhaust gas is low.
The heated oxygen sensor informs the ECM that the post-TWC air-fuel ratio is rich (high voltage, i.e. more than 0.45 V).
The heated oxygen sensor has the property of changing its output voltage drastically when the air-fuel ratio is close to the stoichiometric level.
The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air-fuel ratio after the TWC is rich or lean and adjusts the fuel injection duration accordingly.
Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air-fuel ratio control.
The ECM continuously monitors the heated oxygen sensor output voltage while the engine is running.
The Diagnostic Trouble Code (DTC) P0138 is stored if the heated oxygen sensor voltage output is 1.2 V or higher for 10 seconds or more.
OBDII Code P0138 Toyota - Oxygen Sensor Circuit High Voltage Bank 1 Sensor 2 - Engine-Codes.com
https://www.engine-codes.com/p0138_toyota.html
https://cartreatments.com/p0138/
Code P0138 indicates an issue with the O2 sensor for Bank 1, Sensor 2.
This sensor analyzes the vapors that come out of your catalytic converter.
A regular voltage reading is around .45 volts for the perfect oxygen-to-fuel ratio.
Code P0138 appears when the sensor voltage reaches over 1.2.
The high voltage signals that there is too much fuel and not enough oxygen running through your motor.
Symptoms of Code P0138
You’ll likely notice that something isn’t right with your vehicle if your car shows Code P0138. The obvious sign is your check engine light. But other symptoms will confirm that there’s a problem.
You may see a decrease in your fuel economy. With this code, your vehicle runs rich. This scenario means that there is too much fuel and not enough oxygen going through the engine with each stroke. Therefore, you’ll need to get gas more frequently than before.
When you’re driving or idling, you may notice stronger smells coming from your exhaust. These fumes may have a stronger gas smell than typical exhaust. You might also experience an extremely rough idle.
If any of these symptoms accompany your P0138 code, the problem is not a faulty sensor. Something more significant is happening to your vehicle.
A P0138 Code indicates a problematic voltage reading from your oxygen sensor. It’s possible that this high reading comes from a damaged connection around the sensor. Damage to these wire connections can come from:
- Corrosion
- Power surges
- Shorts in the circuit
If the surrounding connections are functioning, the issue could come from the sensor itself. If your oxygen sensor is faulty or damaged, it can cause a P0138 code.
A dirty catalytic converter will also create artificially high readings on the Bank 1, Sensor 2. Cleaning your catalytic converter with a cleaner designed for the job will likely remedy any remaining issues.
The last part to check, if nothing else seems to be a problem, is the fuel pressure. High fuel pressure causes more gas to run through the engine, impacting the oxygen ratio. A problem with your fuel pressure is a much bigger issue than a mishap with the sensor or connections.
Is Code P0138 Serious?
Driving short distances is not a problem when your vehicle shows a P0138 code. However, you shouldn’t let it go long without examining the underlying cause of the code in the first place.
Running the engine with a higher fuel-to-oxygen ratio does not cause immediate damage to your vehicle. However, it will cost you in fuel efficiency and can cause your exhaust to be less clean. Running your engine rich for a long time will eventually harm your car.
How to Fix
The cost and effort involved in getting rid of a P0138 code depends on the underlying issues that sent the reading.
First, replace any damaged connections or wires that surround the Bank 1, Sensor 2. In many instances, this action eliminates the code with minimal cost and effort.
The second fix involves diagnosing the oxygen sensor itself. It should have a voltage reading around 0.45. Check this voltage with a multimeter. If it reads 0.9 or above, then the sensor may be damaged and need to be replaced.
However, before replacing the sensor, you must be sure that the high voltage reading does not indicate another problem.
Verify that both the coolant temperature and the fuel pressure are within the appropriate ranges for your vehicle. If the coolant and fuel pressure are where they should be, then replace the oxygen sensor to clear the P0138 code.
P0132 – O2（A/F）センサ系統B1S1（High）
0138_toyota.html
https://www.rav4world.com/threads/p0138-o2-sensor-replaced-but-not-fixed-what-else.177449/
P0138 : O2 sensor replaced but not fixed. What else?
I got CEL, VSC, 4WD lights on. Scanned code P0138, bank1 sensor 2 voltage is too high. I replaced post cat O2 sensor to new Denso O2 sensor. But the same lights and code came back soon.
Below are the recorded graphs while I was driving with new O2 sensor. AFR looks okay. Still O2 sensor output voltage stuck to 0.9V. It went low boltage only when I released the accel pedal in decending slope.
What else can I look?
Thanks.
Attachments
Discussion Starter · #4 · Feb 10, 2015
It was bad Air/Fuel ratio sensor.
The OBD data log showed long term fuel trim is +7% or more even though AFR sensor output is in good range.
AFR sensor output shifted to lean and ECM was fooled and injected more fuel.
That's why O2 sensor stuck rich.
After replaced AFR sensor, CEL/VSC/4WD lights were gone and fuel trim%, AFR, O2 data is in normal range.
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https://yarisworld.com/forums/showthread.php?t=62589
I have a CEL P0138 which is high voltage bank 1 sensor 2. I blindly replaced the rear sensor assuming it was bad (original sensor 230k miles). But after about 45 min of driving the light came on with the same code.
Today I tested the new sensor with a multimeter and got the proper 16ohm on pins 1+2, but just got a "OL" reading on 1+4 when it was supposed to be over 10kohm. Is this the proper test as per the FSM? Is it possible my replacement was bad out of the box? (Denso)
Where else should I start to chase this down.
https://obd2pros.com/dtc-codes/p0138/
Meaning
Your vehicle Engine Control Module (ECM) stores a P0138 when it detects the O2 sensor for Bank 1, Sensor 2 fails a voltage test.
The voltage must register below 1.2 volts for over 10 seconds and indicates there is insufficient oxygen in the exhaust stream.
In short, your oxygen sensor is doing its job and your engine’s fuel/oxygen mixture isn’t right, or the sensor is faulty.
Either way, you’ve got to get down to the bottom of this problem.
Causes
There’s three potential causes that will trigger this trouble code. Here’s what to check first when you go to troubleshoot the code:
The engine control module (ECM) registers a spike in voltage above 1.2 volts due to an O2 drop in the exhaust stream. This signals a “lean” fuel condition in the ECM, and it attempts to compensate by altering the fuel/O2 mix..
The ECM registers a voltage spike and stores the code before flipping on your Check Engine Light. This could mean a sensor failure or a fuel/O2 mixture problem.
The ECM is compensating for the high voltage issue by using other engine O2 sensors to alter fuel injector output and balance the fuel/O2 mixture.
Symptoms
How will you know your ECM is coding a possible P0138? Here’s the typical symptoms of the problem:
Your engine may run lean during sensor testing, leading to misfire and hesitation on startup or acceleration
.The Check Engine Light will be illuminated, and you should always pull codes when that indicator lights up on your dashboard.
Your engine may have air intake and fuel system problems depending on the root cause of the sensor voltage spike and subsequent “rich” fuel/O2 mixture.
Symptoms
How will you know your ECM is coding a possible P0138? Here’s the typical symptoms of the problem:
Your engine may run lean during sensor testing, leading to misfire and hesitation on startup or acceleration
.The Check Engine Light will be illuminated, and you should always pull codes when that indicator lights up on your dashboard.
Your engine may have air intake and fuel system problems depending on the root cause of the sensor voltage spike and subsequent “rich” fuel/O2 mixture.
How does a mechanic diagnose the P0132 code?
FFD:
Takes a record of freeze frame data and all trouble codes that have been stored by the power control module (PCM), using an OBD-II scanner
Clears the P0132 trouble code which will turn off the Check Engine Light
Test drives the vehicle to see if the trouble code and check engine light comes back on
Uses the OBD-II scanner to view live data and monitor the voltage levels going to the oxygen sensor to ensure proper voltage
Checks the oxygen sensor wiring for broken or exposed wires
Common mistakes when diagnosing the P0132 code
In most cases, the oxygen sensor will need to be replaced to fix the problem and clear the P0132 trouble code from the power control module (PCM).
It is important not to overlook the oxygen sensor wiring and check for broken or exposed wires prior to replacing the oxygen sensor.
How serious is the P0132 code?
The P0132 trouble code is not widely considered a serious one.The driver may experience an increase in fuel consumption. Also keep in mind that a vehicle in this condition emits harmful pollutants into the air.
https://avtotachki.com/ja/p0132-vysokiy-uroven-signala-v-cepi-datchika-kisloroda-bank-2-datchik-1/
MHO:
P0155:
P0108:
P0130:
P0133:
CO:1.08%
HC:710ppm
CO2:12.6%
O2:3.2%
https://www.team-mho.com/o2senser-627/
