P2213 – Nitrogen oxides (NOx) sensor, bank 2 – circuit malfunction

By Reinier (Contact Me)
Last Updated 2016-12-08
Automobile Repair Shop Owner

Table of Contents

1. What Does Code P2213 Mean?
2. What are the common causes of code P2213?
3. What are the symptoms of code P2213?
4. How do you troubleshoot code P2213?
5. Codes Related to P2213
6. Get Help with P2213

What Does Code P2213 Mean?

SPECIAL NOTES: OBD II code P2213 does NOT necessarily describe a failure of the NOx control system per se; instead, this code more often describes a failure or malfunction of the NOx sensor on a given bank of cylinders. NOx sensors are critically important sensors in an important part of the emissions control system, and for this reason, non-professional mechanics are strongly urged to read the section that deals with NOx (a toxic cocktail of nitric oxide and nitrogen dioxide gases commonly referred to as NOx, or nitrous oxide) control and elimination in the manual for the application being worked on.

Gaining at least a working knowledge of the system, its various components, as well as to how the system interacts with other emission control systems/components is important, since failing to do this could result in a misdiagnosis, the unnecessary replacement of parts and/or components, or fatal damage to expensive emission-control system components, such as the catalytic converter. Also, note that while NOx reduction technologies achieve the same result on gasoline and diesel engines, which is the reduction, if not the complete elimination of NOx, the method used on diesel engines is several orders of magnitude more complicated than that used on gasoline engines.

For this reason, the information presented here is intended for general informational purposes only, and it should therefore NOT be used in ANY diagnostic procedure for code P2213 without making proper reference to the manual for the application being worked on, and especially so where P2213 is present on a diesel application, where this code could be accompanied by many other codes.

Nonetheless, the generic diagnostic information provided in this guide should enable most non-professional mechanics to diagnose, and repair P2213 on most applications, and under most conditions. However, if the code persists beyond the steps outlined in this guide, the better option is to refer the vehicle for professional diagnosis and repair. END OF SPECIAL NOTES.       

OBD II fault code P2213 is a generic code that is defined by all carmakers as “Nitrogen oxides (NOx) sensor, Bank 2, circuit malfunction”, and is set when the PCM (Powertrain Control Module) detects a failure of, or malfunction in, the NOx sensor itself, or the control module/circuit of the NOx sensor. On engines with two cylinder heads, “Bank 2” refers to the bank of cylinders that does not contain cylinder #1. Note that the NOx sensor is used in conjunction with oxygen sensors, and that it therefore performs an entirely different function to the oxygen sensor(s).

NOx sensors are similar in appearance to oxygen sensors, and like oxygen sensors, NOx sensors have to be at very specific temperatures before they will detect NOx in the exhaust stream. Therefore, NOx sensors are fitted with heating elements that are controlled with dedicated circuits to control the heater element.

NOx has been shown to be the chief component in vehicle exhaust gas that causes smog, acid rain, and respiratory distress in some people, but one unintended consequence of making engines more fuel-efficient has been that the more efficient engines became, the more difficult it has become to control the formation, and elimination of NOx from vehicle exhaust gas.

To this end, car manufacturers have developed new technologies, such as 3-way catalytic converters on gasoline applications, and SCR (Selective Catalytic Reduction) on diesel applications. Both technologies are more effective at NOx detection and elimination than EGR (Exhaust Gas Recirculation), or VVT (Variable Valve Timing), which technologies control the combustion temperature in order to reduce the formation of NOx.

On gasoline engines, the NOx is temporarily stored in the catalytic converter, until the dedicated NOx sensor detects that the level of NOx (measured in parts per million) exceeds the permissible level. When this happens, the NOx sensor’s dedicated controller communicates the fact to the PCM via the CAN (Controller Area Network) bus system, upon which the PCM temporarily enriches the air/fuel mixture to raise the temperature inside the catalytic converter to extremely high temperatures in order to allow the catalytic material in the converter to oxidize, or break down NOx into oxygen, water, and other innocuous substances.

Note that air/fuel mixture enrichment typically runs for about two seconds out of every 60 seconds, and that on some gasoline applications, air is injected into the catalytic converter to bring about the required temperature increase, which can be anywhere from about 840⁰F (450⁰C) to around 1560⁰F (850⁰C) or more, depending on the application.

On diesel applications, the SCR (Selective Catalytic Reduction) system injects urea, known as DEF (Diesel Exhaust Fluid) in the USA, and AdBlue in Europe) into the exhaust system. The urea breaks down, or decomposes into ammonia in the exhaust system, where it works in conjunction with highly specialized catalytic materials in the converter to convert NOx into nitrogen and other harmless substances at temperatures of several hundred degrees. Note that this injection system is prone to failure, and that such failures (or contamination of the reductant fluid) can cause a myriad of additional codes to be set, even though the dedicated NOx sensor and its controller may be working perfectly.

The above descriptions are necessarily brief, but they serve to illustrate the point that it is important to have at least a basic understanding of the NOx reduction system in order to be able to diagnose code P2213 correctly the first time. Nonetheless, when the PCM detects a failure of the NOx sensor, or a malfunction in the sensors’ control circuit it will set code P2213, and illuminate a warning light. Note that a flashing warning light indicates a serious problem, which more often than not, is an indication that catalytic converter failure has occurred, or is about to occur.

The image below shows a typical NOx sensor with its dedicated controller. Note that the actual appearance and location of NOx sensors vary between applications.

What are the common causes of code P2213?

This list of possible causes of code P2213 is likely not complete, but as with many other trouble codes, distinguishing between the cause(s) and effect(s) of this code is not always easy, so it is an easy mistake to attribute catalytic converter failure as a leading cause of this code, since NOx sensor failures often cause converters to fail. The fact is that since catalytic converters are extremely durable, the possible causes of code P2213 are much more likely to be the result of causes other than a simple failure of the catalytic converter.

Note that the possible causes of code P2213 listed here can lead to (or sometimes indicate) the failure of both the NOx sensor and the catalytic converter, but bear in mind that if catalytic converter failure occurs, it almost always happens as the result of a failure of the NOx sensor, and not vice versa. Also, be aware that all the possible causes of P2213 listed here will almost always be indicated by one or more codes other than P2213. Below are some possible causes of code P2213-

• Damaged, burnt, shorted, disconnected, corroded, and or open circuits in the wiring of almost any sensor in the fuel/engine management, or emissions control system. Always consult the manual for the application for detailed information on which sensors (and their wiring), apart from the NOx sensor, are most likely to be implicated in setting P2213.
• Malfunctions of, or defects in almost any sensor that controls/monitors the fuel, ignition, VVT/VVC, or emissions control system. Always consult the manual for the application for detailed information on which sensors, apart from the NOx sensor, are most likely to be implicated in setting P2213 on the application being worked on.
• Use of unsuitable, contaminated, or poor quality fuel.
• Use of contaminated DEF (Diesel Exhaust Fluid). In some, if not most cases where DEF contamination is a contributing factor, it may be necessary to replace the entire DEF injection system to resolve P2213.
• Low DEF fluid level.
• Misfires on one or more cylinders. Note that the cause of the misfire(s) is largely irrelevant to the setting of P2213; however, all misfires MUST be resolved before a diagnosis of P2213 is attempted.
• Exhaust leaks anywhere in the exhaust system, especially upstream of the catalytic converter, can be seen by the PCM as a failure of the converter, since upstream exhaust leaks often interfere with the operation of oxygen sensors.
• Abnormal system voltages. Note that NOx sensors require full battery voltage for the heater element to work as designed. Low system/battery voltages can cause the heater element not to work properly, while excessive voltages can damage the element, which has the same result. Note however that some applications use a dedicated system to boost low battery voltages to assist in the heating cycle of the NOx sensor. Consult the manual for detailed information on the operation of this booster system.
• Note that aftermarket or rebuilt catalytic converters offer neither the efficiency, nor the durability of OEM catalytic converters, and more often than not, the use of substandard converters is the direct cause of this code.
• Unauthorized modifications or alterations of the exhaust system can also cause this code. Note that some types of modification constitute tampering of the emissions control system and are therefore illegal.
• PCM failure. Note however that in light of the multitude of possible causes of P2213, PCM failure is a highly unlikely event, and with the exception of the NOx sensor controller that comes with the sensor, the fault must be sought elsewhere before any controller is replaced.

What are the symptoms of code P2213?

Since many causes of P2213 can be the result of failures and malfunctions in systems that seemingly are not directly related to the NOx sensor and its controller, it is not possible to provide a list of symptoms here that will always be present on all applications all of the time- beyond a few symptoms that might be present on most applications.

Always consult the manual for the application for detailed information on the symptoms that are most likely to be present on that application. Having said that, below are some symptoms other than a stored trouble code and illuminated warning light that may or not be present, depending on the application and the exact nature of the problem-

• Some applications may experience a loss of power that can range from slight, to severe
• Misfire conditions may develop, or worsen in some cases
• Catalytic failure may occur
• No start conditions may develop
• Engine may idle roughly, erratically, or the idle sped may fluctuate wildly
• Engine may stall frequently, or unpredictably
• Engine may hesitate or stumble upon acceleration

How do you troubleshoot code P2213?

SPECIAL NOTES: It is important to note that P2213 can be accompanied by many other codes, such as one or more of the following- P2200, P2201, P2202, P2203, P2204, P2205, P2206, P2207, P2208, P2209, P2210, P2211, P2212, P2214, P2215, P2216, P2217, P2218, P2219, P2220, P2221, P2222, P2223, P2224, and P2225.  

However, the number of additional codes depends on the application and the exact nature of the problem, which is why it is important to note where in the list of [possible] additional codes P2213 appears. If P2213 appears as the first code, all other codes are the result of P2213, but if P2213 appears further down the list the preceding codes are contributing factors that caused P2213, with the codes following being the result of a combination of P2213 and those that came before it.

All additional codes should always be investigated and resolved in the order in which they were stored, since in many cases, resolving the first few codes will resolve all other codes. This is particularly true of P2213, but reading the relevant the section(s) in the manual, and gaining at least a basic understanding of the NOx control mechanism on the application being worked on before attempting a diagnosis of P2213 will make it easier for non-professional mechanics to distinguish between the possible cause(s) and the most likely effect(s) of code P2213. END OF SPECIAL NOTES.  

WARNING: DO NOT attempt to diagnose this code, or try to “test” the functioning of the catalytic converter by deliberately inducing misfires under ANY circumstances. Doing this could raise the catalytic converter temperature dramatically, and in severe cases, some types of misfire, such as when spark plugs are deliberately disabled, can cause a catalytic converter to melt in as few as 10-12 seconds. Be aware that apart from the expense that goes with replacing a catalytic converter, an overheated converter can set a vehicle on fire, which is even more expensive to replace.

NOTE #1: An infrared thermometer with a laser pointer is a required item when diagnosing P2213, since the actual temperature of the catalytic converter(s) is an important diagnostic aid in resolving this code.

NOTE #2: Diagnosing code P2213 can be made a whole lot easier if the vehicle can be placed on a vehicle hoist, or lift. If a hoist is not available, jack up the vehicle as high as possible, and use approved jack stands to support the vehicle while working under it.   

Step 1

Record all fault codes present, as well as all available freeze frame data. This information can be of use should an intermittent fault be diagnosed later on.

WARNING: If other codes are present along with P2213, note the order in which the codes were stored, and be absolutely sure to resolve all codes in the order in which they were stored before attempting a diagnosis of this code. Refer to the WARNING above. Pay particular attention to system voltage related codes if any are present, since abnormal system voltages affect the correct operation of almost all sensors on any application. In some cases, it may be possible to resolve a raft of codes simply by resolving a system voltage related code.

Step 2

Although a common cause of P2213 is a failure of the catalytic converter, it must be stated that catalytic converters generally do not fail unless a failure or malfunction somewhere else in the emissions control-, or engine management system, such as a misfire on one or more cylinders directly causes the catalytic converter to fail.

However, one exception to this rule is the fact that catalytic converters become less efficient as they age, even if no exceptional circumstances are present. Thus, the next thing to do is to check whether the converter is still covered by a warranty; federally mandated warranties can run from 80 000 miles to 150 000 miles in some cases, so check this with the authorities in your state.

Be aware though that replacing a catalytic converter that is under warranty is best left to specialist repair shops and/or dealers in order to avoid legal issues and ramifications.

Step 3

Assuming that there are no other codes present or that all other codes have been resolved, start the engine, and allow it to warm up to normal operating temperature to ensure that the NOx sensor has entered closed loop operation, which happens when it starts to generate a feedback signal.

Next, point the laser thermometer at a point close to where the exhaust pipe enters the catalytic converter and not the value once the reading has stabilized. Repeat the procedure at a point where the exhaust pipe exits the converter, and note this value for future reference as well as well.

NOTE: On some applications, it is necessary to run the engine at a specified speed before obtaining temperature readings, so consult the manual for the application on this very important point.

Compare the obtained readings with those stated in the manual, and note any discrepancies found. A small discrepancy at this point is not necessarily proof of a defective converter, but be sure to double check the temperature if there is any doubt about their accuracy. Temperature readings that agree with specified values exactly are rare, but not impossible, so do not draw any conclusions as to the serviceability (or otherwise) of any component based purely on obtained temperature readings.

Step 4

Allow the exhaust to cool down while consulting the manual on the location of the NOx sensor, as well as on the location, function, color-coding, and routing of all wiring associated with the NOx sensor.

Perform a thorough visual inspection of all associated wiring, including fuses where fitted. Look for damaged, burnt, shorted, disconnected, and/or corroded wiring, and pay particular attention to the connector where the NOx controller connects to the general wiring harness. Check the pins in the connector for corrosion and/or damage, and make repairs as required. Clear all codes after repairs are complete, and rescan the system to see if the code returns.

Step 5

If no visible damage is found, prepare to perform reference voltage, ground, resistance, and continuity tests on all wiring, but be sure to disconnect the sensor from the wiring harness to prevent damaging the PCM during this step. Always perform this type of test with the aid of a pin-out diagram obtained from official sources to avoid causing short circuits that could damage other components.

Compare all obtained readings with those stated in the manual, and be sure to consult the manual for recommended repair options if discrepancies are found. Communication between the NOx sensor controller and the PCM takes place on the CAN bus system, which means that simply repairing damaged or non-functional wiring could have serious consequences for the continued correct functioning of parts of the CAN bus system. Therefore, do NOT deviate from recommended repair options.

NOTE #1: Bear in mind that since the actual NOx sensor forms part of the control circuit it must be tested as well, but be sure to consult the manual for detailed information on how to test the sensor correctly to obtain reliable and accurate results. Compare all readings obtained on the sensor with the values specified in the manual, and replace the sensor if ANY reading falls outside the specified range or value.

NOTE #2: On some applications, the ground is supplied by the PCM, so consult the manual to determine the correct procedure (KOER/KOEO) to establish the ground connection.

NOTE #3: On some diesel applications, the reference voltage is supplied via the glow plug control circuit. Consult the manual to determine the correct testing procedure to avoid damaging the glow plug control unit and/or other controllers.

Step 6

When replacing the NOx sensor, make sure all connections are secure and that all wiring is secured away from hot exhaust components to avoid damage to wiring. Clear all codes.

Next, start the engine and allow it warm up to normal temperature to ensure that the new sensor enters closed loop operation- this is a required step to be able to recheck the catalytic converter temperature. Assuming that the entire emission control system is fully functional, the NOx sensor is the “switch” that regulates the NOx reduction component of the emission control system, so if the sensor works as it should, this will be reflected in the catalytic converter temperature.

Take temperature readings for at least 2 minutes at both ends of the converter, but be sure to follow the directions in the manual with regard to engine speed, and throttle activation to ensure accurate results. If the NOx sensor is good and there are no other codes present, but the converter temperature deviates from the values stated in the manual by more than a few percent, suspect a defective converter.

NOTE: Be aware that fuel quality (and fuel type) has a direct bearing on exhaust temperatures and catalytic converter efficiency, and especially so if pure biodiesel or diesel blends that exceed ~20% biodiesel content is used. Biodiesel contains more oxygen than regular diesel does, and since free oxygen availability in various parts of the converter plays a critical role in NOx reduction, any excess oxygen may very well cause the actual converter temperatures to deviate from recommended values. 

Step 7

If the actual, measured temperatures of the catalytic converter closely match the values specified for the application, it is almost certain that the repair had been successful. However, it would be prudent to test the system under real-world diving conditions, so operate the vehicle for at least two or three drive cycles with a scanner attached to monitor the operation of the NOx sensor in real time.

If no codes return after the test drive, the repair was successful, but be aware that any damage the catalytic converter may have suffered while the NOx sensor was inoperative may be reflected in the readings obtained from the new NOx sensor during the test drive. If damage to the catalytic converter is suspected, refer the vehicle to the dealer or specialist repair shop for professional diagnosis and repair, which repair could include replacement of the converter.

Codes Related to P2213

• P2214 – Relates to “NOx Sensor Circuit Range/Performance Bank 2”
• P2215 – Relates to “NOx Sensor Circuit Low Bank 2”
• P2216 – Relates to “NOx Sensor Circuit High Bank 2”
• P2217 – Relates to “NOx Sensor Circuit Intermittent Bank 2”

NOTE: The four codes listed above are the codes that are most closely related to P2213. Refer to the SPECIAL NOTES in the Troubleshooting section of this guide for details on other codes that are often associated with P2213.

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