Error Code P2042: What It Means & What To Do?

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Error code P2042 flashing? All you need to do is use this little guide by Parts Avatar to solve the error code P2042. A pickup tube for reductant pump module, an electric heating element, a reductant temperature sensor and an electrode type level sensor constitute the reductant heater and sender assembly. One can locate the heating element above the pickup tubes inlet filter. The powertrain control module orders the glow plug control module to provide voltage to heating element when the reductant temperature sensor identifies the diesel exhaust fluid temperature dropping to the freezing point of 12°F (-11°C). The liquid reductant is melted by the heating element within the reductant heater and sender assembly reservoir during cold ambient temperatures.

It should be noted that a reductant compound or a diesel exhaust fluid (DEF) is injected by the SCR systems into the exhaust located in front of the diesel particulate filter, NOx trap and/or the catalytic converter through the reductant injection valve (solenoid). The temperature of the filtration element is elevated by the accurately timed DEF injection which further allows it to function more efficiently. This increases the longevity of the filtration element allowing fewer harmful exhaust emissions to be released into the atmosphere. A stand-alone controller (which interacts with the PCM) or the PCM itself monitors and controls the entire SCR system. To determine the accurate time for the DEF (reductant) injection the controller regulates the O2, NOx, and exhaust temperature sensors (along with other inputs). The right DEF injection is required to maintain exhaust temperature within adequate parameters also to enhance the pollutant filtration.

What causes this problem with the Reductant Temperature Sensor Circuit ?

• Defective reductant temperature sensor
• The harness in the reductant temperature sensor that are burnt or loose
• A weak electrical connection in the reductant temperature sensor circuit 

1. Reductant pump module - Don’t know what problems can be caused due a faulty reductant pump module? It can cause leakages in the reductant fluid tanks or lines along with an error code P2042. Mend or restore it now!
2. Exhaust gas temperature sensor - Having problems with the exhaust gas temperature sensor? Well, it is likely to invite issues like failed emissions tests along with a flashing check engine light. Tune into Parts Avatar for your new exhaust gas temperature sensor.
3. Catalytic converter - Now get rid of engine misfiring and degraded engine performance by simply replacing or repairing your catalytic converter. Visit us today to grab amazing offers on premium quality parts.
4. Powertrain control module - This essential unit often regarded as the backbone of the entire system, if defective, should be changed as soon as possible if you want to get away with all the problems caused by the error code P2042.
5. Exhaust system parts - Low power during accelerations? Reduced engine performance? Yes, all this is likely caused due to a fault in the exhaust system parts. Change or repair now if you wish to save your hard earned money and precious time.
6. Reductant injection valve - Are you observing a reduced fuel efficiency? Off-throttle braking? All this is likely to accompany a damaged reductant injection valve. We advise you to get it changed immediately. Log into Parts Avatar for your new reductant injection valve now!

It is vital to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD code P2042 here:

Common Symptoms

• The check engine light flashing (or service engine soon warning light)
• Black smoke emitting upon acceleration
• Apart from this there aren’t any obvious signs other than an illuminated service engine soon lamp and the stored trouble code

Want to correct the trouble code P2042? Read these points mentioned below:

• Repair or replace your malfunctioning reductant temperature sensor
• Make sure repairs or replacements are being made of the poor electrical connection running in the reductant temperature sensor circuit
• All the corroded or loose harness in the reductant temperature sensor should be replaced or repaired

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It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P2042 code to be stored:

• It should be noted that the reductant injection systems present are utilized in all types of vehicle exhaust systems but are mostly found in the diesel applications. The reductant injection systems make use of water, a chemical agent, air, or a combination of the three in order to decrease the exhaust emissions that takes place in automotive applications by reducing exhaust temperature and/or exhaust pressure in the diesel particulate filter or catalytic converter assembly.
• One can locate the reductant injector on the diesel particulate filter or catalytic converter.
• Generally, it is monitored electronically utilizing a dedicated reductant injector controller (used in conjunction with the PCM).
• When a strangely high exhaust temperature, pressure, and/or toxic gas concentration is identified by the PCM, this actuates the reductant injector and the reductant compound is sprayed into the diesel particulate filter or catalytic converter.
• This reductant compound further aids in decreasing the exhaust gas temperature and/or pressure or harmful gases.
• This sensor is a 2 wire sensor located in the exhaust down pipe. Also, the exhaust gas temperature sensor is utilized in diesel engines, gasoline burning engines and even turbocharged engines.
• The sensor can be located near the diesel particulate filter section of the exhaust system in diesel engines. While the turbocharged applications are often place the exhaust gas temperature sensor in the exhaust input pipe nearby the turbocharger.
• The exhaust gas temperature sensor installed is of the temperature reactive resistor variety and is supplied with a low voltage (usually 5-volts) power wire and a ground wire.
• The level of resistance in the sensor falls, further enabling the feedback voltage signal to the PCM to increase as the exhaust gas temperature increases.
• Consequently, as exhaust temperature reduces (with the engine off), both the circuit resistance and the feedback voltage signal to the PCM decrease
• All these voltage variations are recognized by the powertrain control module as the exhaust gas temperature and it reacts in accordance thereby adjusting ignition timing or the air/fuel ratio in order to reduce the exhaust gas temperature and save the catalytic converter. When the PCM commands the reductant injector “ON” it starts monitoring the upstream and downstream exhaust gas temperature, exhaust gas pressure, or heated oxygen sensor/s to determine if there is the required reduction temperature, pressure, or harmful gas levels.
• The code is stored followed by an illuminated service engine soon lamp if the downstream levels fail to display significant reduction.
• While performing the diagnosis numerous tools are instrumental in successfully diagnosing this code.
• All that is required for a successful diagnosis is an appropriate OBD-II scanner (or code reader), digital volt/ohmmeter and an infrared thermometer (with a laser pointer).
• Proceed further to a visual inspection of all wiring and connectors. All the damaged, disconnected, shorted wiring, connectors or electrical components should be repaired or replaced as per the requirements.
• Then the system should be retested after all repairs have been performed to ensure success. If in case all system wiring, connectors, and parts (including fuses) are functioning in normal working order, the scanner (or code reader) should be connected to the diagnostic connector to retrieve all stored codes and freeze frame data as this information is highly essential in diagnosing intermittent conditions that may have contributed to this code being stored.
• Next, the codes present should be cleared again and the vehicle should be test driven to to see if it returns. Well, this helps greatly in determining whether or not the defect is intermittent.
• Next, if the codes have been cleared, perform a test drive to see if the error persists. If in case the code fails to appear immediately, you may have an intermittent condition.
• It should be noted that these intermittent conditions can often prove to be quite difficult to diagnose and in extreme cases may need to worsen before an accurate diagnosis can actually be made.
• Proceed further with your diagnosis of the exhaust gas temperature/pressure (or heated oxygen) sensors and system circuitry.
• Closely attend to the areas where wiring and connectors are located(near hot exhaust components).
• Now if all the exhaust gas temperature/pressure (or heated oxygen) sensor circuitry is functioning in order, proceed further.
• All the components that appear to be defective or corroded should be repaired or replaced. Reset the code and retest the system. If you find no damaged or shorted wiring or loose connectors, disconnect the exhaust gas temperature/pressure (or heated oxygen) sensor connector and detach the exhaust gas temperature sensor.
• The digital volt/ohmmeter should be used to check the resistance of the exhaust gas temp/pressure (or heated oxygen) sensor.
• Generally. The resistance for this sensor should range approximately to 150 ohms but the manufacturer’s specifications should be checked twice prior to testing.
• If there resistance less than 50 ohms, you should replace the sensor.
• Also, leave the leads of the digital volt/ohmmeter connected and heat the resistor with a heat gun if the initial resistance is within specifications. Then observe the resistance level of the sensor (on the screen of the digital volt/ohmmeter) as the temperature increases to see if it decreases smoothly.
• Well, if the resistance level fails to reduce with heat and increase as it cools, the sensor should be replaced.
• Now that everything has been checked carefully, next you should turn the key to the “ON” position to test for the presence of a voltage (and a ground signal) at the exhaust gas temperature/pressure (or heated oxygen) sensor electrical connector.
• Disconnect the PCM connector and perform a continuity test on the wire using the digital volt/ohmmeter if there is no low voltage (usually 5-volts) on the signal wire.
• Most likely the PCM is at fault (although a failure in the PCM is rare and, if replaced, it will need to be reprogrammed) if there is continuity.
• Locate the source and check for continuity using the digital volt/ohmmeter if there is no ground is present.
• All the loose or short circuited wiring and connectors should be repaired or replaced as required. If there is no voltage present on the sensor connector and all system circuitry is functioning in order, a malfunctioning reductant injector air controller should be suspected.
• Also, a fault in the controller is rare and will likely require reprogramming. Often, the installation of high performance exhaust systems (with no catalytic converters) can also cause this code to be set due to the less exhaust system back pressure.
• You can correct this condition by simply installing an in line resistor (2.5 ohms) between the signal and ground wires and leaving the exhaust gas temperature sensor detached.
• The PCM reads the sensor resistance and passes it.
• All the local, state, and federal laws should be checked carefully before removing emission related components

Common Mistakes When Diagnosing the P2042 Code

Here we have listed a few common mistakes that should be avoided while diagnosing the error code P2042:

Mistaken identity is the most commonly committed mistake. Most of the times, the oxygen sensor is mistaken for the exhaust gas temperature sensor or one gets confused believing that the exhaust gas temperature is unified in the heated oxygen sensor. This wrong replacement of the oxygen sensor becomes the reason behind an unsuccessful diagnosis.