P0138 code

P0138 code

Quite a few Toyota vehicles are experiencing a Corolla P trouble code. P extremely high voltage short is set when the oxygen sensor reports voltage above 1. Sensor 2 is located after the catalytic converter and should normally produce a near flat line response.

P0140 P0138 Code Chevy Truck (Check This First)

This Toyota test is called active air fuel ratio control. The computer forces a rich or lean mixture into the engine and then reads the results from the oxygen sensors to see if they respond in a predicted manner. The connector has 4 wires. Terminal 1 pink is fused battery voltage for the sensor heater and terminal 2 is the ground for the heater.

With the key in the RUN position, check for battery voltage on terminal 1 and 5-volt reference on terminal 4. Check for good ground on terminal 2. If the voltages and ground check out, look for corrosion in the connector due to water dripping on the connector from the AC condensate drain. Also check for chaffing on the wiring harness.

p0138 code

Both are well known problems that can result in a Corolla P trouble code. Unlike the cheaper Haynes and Chilton manuals that cover multiple year models, leaving the exact information you need to fix your car, these professional manuals cover your exact year, make, model. Plus, they contain full trouble code descriptions and troubleshooting instructions. Pricing: Eautorepair.

Check Engine Light Code P0138: Why You Shouldn’t Assume It’s a Worn Oxygen Sensor

So you have to refer to the factory legends to learn the identification symbols and then refer back to circuit diagrams to find the splice and ground locations. However, Alldatadiy. If you need to dig into your doors, dash or console, Alldatadiy. Find this article useful? Share it! Categories Corolla Toyota powertrain P trouble codes.

Tags Corolla P Prominent words 5-volt reference battery voltage catalytic converter corolla p corolla p trouble corolla p trouble code oxygen oxygen sensor oxygen sensors p p trouble p trouble code sensor sensor 2 terminal terminal 1 terminal 2 terminal 4 trouble trouble code.Visually inspect the related wiring harness and connectors.

Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins. What does this mean? Cost of diagnosing the P code Labor: 1. The auto repair labor rates vary widely across the country, and even within the same city. When is the P code detected? The P code is set when the Engine Control Module ECM detects that the rear O2 sensor signal voltage remains excessively high for an extended period of time. For optimum catalyst operation, the air-fuel mixture air-fuel ratio must be maintained near the ideal stoichiometric ratio.

The HO2S output voltage changes suddenly in the vicinity of the stoichiometric ratio. The HO2S generates a voltage between 0.

p0138 code

If the oxygen in the exhaust gas increases, the air-fuel ratio becomes Lean. If the oxygen in the exhaust gas decreases, the air-fuel ratio becomes Rich.

P More Information Need more information on how to fix the P code? Get Access to Factory Service Manuals. Related Information. Repair Importance Level: 2. Why is the Engine Light ON?This indicates there is a failure to have a low voltage output below 1. The O2 Sensor could be functioning improperly, or there could be a lack of continuity in the wiring to the ECU, or it is possible that power is not supplying sufficient enough voltage to the sensor.

This sensor monitors oxygen levels in the exhaust stream. In order to check the O2 Oxygen Sensor Circuit High Voltage Bank 1, Sensor 2, the scanner will show the P code, which indicates the error, and the following should complete the checklist:.

Fouling would indicate a rich fuel mixture of more fuel than oxygen. This could cause fouling of the O2 sensor. Oil or coolant from an engine leak making its way into the exhaust system could be another cause for fouling. Check for damage to exhaust pipes and catalytic converter. Check wiring harness for melted wires especially near hot exhaust parts. Do a visual check of the connections as well as using a Volt Ohm meter for wire connections.

Another cause could be a damaged or clogged catalytic converter. A leaking fuel injector could possibly be another cause. The number one most common repair for this problem is replacing the O2 Sensor itself. Another repair would be to replace the wiring or connection for Bank 1, Sensor 2.

If the catalyst is the problem, replace the catalytic converter. Replace the fuel injector if it is leaking. After repairs have been made, clear stored codes from the ECU and test drive the vehicle between miles per hour for about two miles. If the Oxygen O2 Sensor signal ever goes to a negative voltage, or in excess of one volt, this is indication that the sensor is bad. These inconsistent readings are often the reason to believe the circuit is losing voltage or ground into the O2 Sensor circuit.

If the O2 Sensor body has a chalky appearance, this indicates lag between phases and should be replaced. Remember me. Table of Contents. Subscribe to our mailing list.This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. P is the OBD-II generic code indicating the O2 sensor for bank 1 sensor 2 fails to have a lower voltage output below 1.

The engine control module ECM sees the voltage of the O2 sensor for bank 1 sensor 2 above 1. The engine may run lean during the testing of the sensor to correct the problem and may hesitate or misfire. Monitors O2 sensor data to see if the voltage is switching back and forth between low and high at a fast rate compared to other sensors.

O2 sensor 1 for bank 1 can be used to diagnose O2 sensor 2 for bank 1 by looking at both sensors operation for comparison. The operation should be nearly the same, except sensor 2 should have a lower O2 reading since the catalyst should burn off the excess fuel and oxygen.

Check Engine Light Code P0138: Why You Shouldn’t Assume It’s a Worn Oxygen Sensor

The voltage output from the O2 sensor may be due to the exhaust catalyst being broken apart, which can cause the O2 sensors to give high output voltages.

The ECM may not control the fuel-to-air ratio of the engine properly, leading to a clogged catalyst and excessive carbon buildup in the engine with fouled spark plugs. The high voltage condition from the O2 sensor is indicating a lack of oxygen in the exhaust or other related problems, such as a leaking fuel injector or a broken up catalyst inside.

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at With YourMechanic you can skip the auto shop altogether. They send certified and screened mechanics straight to your door and enable you to save big on car repair and maintenance. Cost of diagnosing the P code.

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P code. Recent Check Engine Light is on Inspection reviews. Excellent Rating. Average Rating 4. Number of Reviews 5, Rating Summary. Kenneth 7 years of experience. Request Kenneth. Kenneth is clearly a first-rate mechanic. He thoroughly inspected our vehicle and found that the engine light was on because of a crack in the filler neck hose. Rigoberto 10 years of experience. Request Rigoberto. This is my first time using Your Mechanic.

Rigoberto arrived earlier than the appointment time. He was very knowledgeable, helpful and answered all my questions. Jason 14 years of experience. Request Jason. Jason was a pleasure to work with. He went above and beyond on my car and it was very much appreciated. Jason worked on my car for 4 days and he was very professional and punctual.The primary purpose of the OBD-II system is engine management with a secondary focus on emissions reduction.

It continuously sends signals back to the engine control computer to adjust the amount of fuel and air going into the engine cylinders. This helps to reduce exhaust emissions. An HO2S is designed to function efficiently for 90, tomiles, depending upon the automaker.

Once the oxygen sensor stops performing as intended, the vehicle computer detects that and turns on the Check Engine light. This will usually have a diagnostic trouble code DTC of P Why is that? When an HO2S fails to respond efficiently, your engine will be firing with too much fuel and not enough air or vice versa.

In most cases, excessive fuel that is not burned by the engine is initially deposited in the intake and cylinder heads. This fuel eventually makes its way into the crankcase, where it contaminates the oil and hinders lubrication.

Lack of engine lubrication can shave years and thousands of miles from the life of an engine. Left unchecked, this rich or lean condition can also damage other emissions sensors, cause ignition system problems, ruin the catalytic converter or lead to internal engine failure.

At that point, what would have been a few hundred dollars to replace a sluggish HO2S has mutated into a problem that may cost thousands. These include:. As you can see, the list goes on and on. This is why we always recommend a complete diagnosis. The part is replaced, but the problem persists. If it is the engine light, see if the gas cap is to blame. From there, we can provide an accurate cost estimate for the repair. See our detailed guide on how to respond when a dashboard warning light turns on.

Have questions about a check engine light or need to schedule an appointment?Meaning of P engine trouble code is a kind of powertrain trouble code and when your car's 'P Check Engine' light comes on, it's usually accompanied by a sinking feeling in the pit of your stomach. The light could mean a costly problem, like a bad catalytic converter, or it could be something minor, like a loose gas cap. But in many cases, it means at minimum that you'll be visiting the car dealer to locate the malfunction and get the light turned off.

Is the fuel pump sometimes not priming when you turn the key to ON II? Start by measuring the fuel pressure and checking whether you have bright white-bluish spark at all four plugs. The mechanical timing is also something that you should check, as we mentioned above. P DTC specifically refers to the camshaft cam timing. In this case, if the cam timing is over-retarded, the engine light will be illluminated and the code will be set.

Engine trouble codes resource center for all car models. Code Search Please fill the "Code Box" to find engine fault code. Select Abadal Schneider Th.

p0138 code

Clubsport Yes! Ways to read engine trouble codes. Ways to clear check engine light on car panel. Check Engine Light Dictionary Ways to clear check engine light on car panel. P Engine Trouble Code Meaning of P engine trouble code is a kind of powertrain trouble code and when your car's 'P Check Engine' light comes on, it's usually accompanied by a sinking feeling in the pit of your stomach.

P Fault Symptoms : Check engine light comes on Engine stalling or misfiring Engine performance issues Car not starting If one of these reasons for P code is occuring now you should check P repair processes. Now don't ask yourself; What should you do with P code? For optimum catalyst operation, the air fuel mixture P code. Check engine light comes on Engine stalling or misfiring Engine performance issues Car not starting. If one of these reasons for P code is occuring now you should check P repair processes.So you should chech it on our car models.

Theoretically you can drive for a few weeks or even months with a broken MAF sensor. You will notice a decrease in gas mileage and over time the car will eventually start stalling a lot. The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. P DTCs may also be triggered by faults earlier down the line. For example, a dirty MAF sensor might be causing the car to overcompensate in its fuel-trim adjustments.

As a result, oxygen sensors are likely to report fuel mixture problems. Engine trouble codes resource center for all car models. Code Search Please fill the "Code Box" to find engine fault code. Select Abadal Schneider Th. Clubsport Yes! Ways to read engine trouble codes. Ways to clear check engine light on car panel. Check Engine Light Dictionary Ways to clear check engine light on car panel. For optimum catalyst operation, the air fuel mixture P code.


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