Guide To P04A3 OBD Error Code Solutions

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Ever came across the OBD code P04A3 in your vehicle? Did it show any problems or leaks in the exhaust pressure sensor, PCM? Then, just give a read to know how to solve this issue. OBD-II Code Powertrain Control Module (PCM) failure can arise due to Exhaust Pressure Control Valve " B" Intermittent

Generally, the exhaust back pressure is controlled by the Exhaust Pressure Control Valve as the engine warms up. If an incorrect signal is detected by the engine control module (PCM) from the Exhaust Pressure Control Valve, P04A3 code will be set by the PCM.

During cold ambient temperature, the Exhaust Back Pressure Regulator controls the exhaust back pressure to rise cab heat and decrease the time when needed to melt the windshield. The Engine Control Module (ECM) uses the calculated exhaust back pressure, (ambient) intake air temperature, engine oil temperature and load to analyse the preferred exhaust back pressure. Control the valve position by changing the output signal circuit to 12 volts present inside the ECM. Depending on the exhaust back pressure, modulate the on/off time from 0 to 99%. Upon each initial engine start-up, the exhaust back pressure valve is exercised by the ECM by commanding it to cycle on and off once.

During the start of engine, if the temperature of the oil sensed by the Engine Oil Temperature (EOT) sensor is between 32°-140°F (0-60°C), and the intake air sensed by the Intake Air Temperature (IAT) sensor is < 37°F (5°C), the valve of the back pressure will remain half shut. The ECM will be controlling the valve in response to the oil temperature rise during the engine operation.

What causes this problem with the Exhaust Pressure Control Valve " B" Intermittent

• A Block in the tube between the exhaust manifold and the pressure sensor
• Leakage in the Exhaust system / Air Inlet / Charge Air
• An Intermittent opening in the ground circuit to the exhaust pressure sensor
• An Intermittent opening in the signal circuit from the exhaust pressure sensor to the PCM (powertrain control module)
• Intermittent supply of voltage in the signal circuit to the exhaust pressure sensor
• Over boosting the Exhaust Gas Pressure Sensor/ turbocharger
• Fault in the PCM

1. Powertrain Control Module - Get your right replacement part for every make from Parts Avatar at an affordable price online.
2. Exhaust Pressure Control Valve - Found a leak in your exhaust pressure control valve? Get rid of it immediately.
3. Exhaust Pressure Sensor - A fault or leak in the exhaust pressure sensor can give rise to this error. Repair them as soon as possible.
4. Engine Control Module - Replace your engine control module with a new one if there are any faults from Parts Avatar.
5. Exhaust Gas Pressure Sensor - If there are any burnt or leaky location in your exhaust gas pressure sensor, repair it immediately to avoid this error coming up.
6. Exhaust system - Any fault in the exhaust system can give rise to trouble. Identify and repair them instantly.

We at Parts Avatar Canada care for our customers, and that’s why we will help you to diagnose P04A3 code by listing out some major symptoms. They are mentioned below as follows:

Common Symptoms

• A well-lit Malfunction Indicator Lamp (MIL)
• Power insufficiency
• Deficiency of engine brakes
• Warm up time of the cold engine is lengthier than normal

Learn the ways with which you can correct this P04A3 trouble code:

• Replacement of Powertrain / Engine train control module.
• Repairing the exhaust gas pressure sensor / exhaust pressure sensor.
• Exhaust pressure control valve / exhaust system replacement.

Don’t get tensed if you are still facing any of these issues as we care for our customers and that’s why we offer a good range of Powertrain Control Module, Exhaust Pressure Control Valve, Exhaust Pressure Sensor, Engine Control Module, Exhaust Gas Pressure Sensor, Exhaust system and a lot more. We are sure that now all your issues would be resolved.

It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P04A3 code to be stored:

• Always start searching for the technical service bulletin (TSB) for your particular vehicle. Us the PCM flash / reprogram which your vehicle manufacturer has and use it to check for this issue so that you don’t have to go along way down the wrong path (powertrain control module).
• Validate if there are any exhaust leaks and listen carefully for exhaust noises coming from manifolds and pipes, and if any black soot is present at the area of the leak. If a leak is present, patch-up the exhaust leak first.
• Now try locating the “B" Exhaust Pressure Sensor and check for any broken wires and connections. See if there are any burn spots, molten plastics, chafing, rubbing or bare wires. If you come across anyone pull them apart and check the terminals in the connectors. See if they are green in colour rather than normal, burnt or even crooked. If you find any of the issues clean them with the help of electrical contact cleaner which you can get from any parts store. Alternatively, you can also use 91% rubbing alcohol and a light plastic brush to clean the burnt spots. Allow them to try and apply some dielectric silicone compound around the terminals where they can come in contact.
• Also, if your vehicle is well-found, try removing the sensing tube which connects the exhaust back pressure sensor to the exhaust manifold. Try blowing through it. If you are unable to blow, then this can also be a possible cause for this code.
• Check if the codes return when you clear the diagnostic trouble codes with the help of a scan tool. If the code is not found, then the problem was mainly because of the connections.
• If the code returns, verify the proper functioning of turbocharger boost operation. Use a scan tool can to read turbocharger boost pressure and look closely for the intake manifold pressure, as it will give the same information. Note down the pressure when it is Key On, but with Engine Off. You can now test drive at a safe speed my accelerating it to a large open throttle. After that start the engine, drive the vehicle at a safe speed, and then momentarily accelerate it to a wide throttle. Make sure the RPM falls between 2500- 3000 RPM’s. You will be shown a jammed/ faulty wastegate, restriction of the exhaust or fault in the turbocharger if the boost pressure is not at least 18.
• If the test has passed, or if you were unable to check the boost of turbocharger, you will have to test the sensor and its connected circuits. Naturally there are 3 wires at the Exhaust Pressure sensor.
• Disconnect the wire going to the Exhaust Pressure Sensor. Test the 5V power supply circuit which goes to the sensor with a Digital Volt Ohm Meter (DVOM), to ensure it is being powered up (Red lead is connected to the 5V power supply circuit, black lead is connected to a good ground). If there is 12 volts instead of 5 volts to the sensor, repair the wires from the PCM to the sensor for a short to 12 volts, or it can also be a failed PCM.
• See if you have 5V on the Exhaust Pressure Sensor signal circuit (Red lead should be connected to the sensor signal circuit; black lead should be connected to a good ground). If there is 12 volts instead of 5 volts to the sensor, repairing the wire from the PCM to the sensor can be the best option or it can also be a faulty PCM.
• Check for a good ground at the Exhaust Pressure sensor. Connect one end of the test light to 12V battery positive (red terminal) and connect the other end of the test light to the ground circuit that leads to the
• Exhaust Pressure Sensor circuit ground. If it does not light up, it will indicate the problem in the circuit. If it lights up, shake the wiring connect which goes to the exhaust pressure sensor and see if the test light flickers, which indicates a loose connection.
• Despite all the above test, if you still continue to get a P04A3 code, it can mainly be due to a fault in the Exhaust pressure sensor and don’t miss the PCM until the sensor has been replaced.

Common Mistakes When Diagnosing the P04A3 Code

• Fault in the Exhaust pressure control valve
• Fault in the Powertrain Control Module (PCM)
• Wire issues.