P2218 NOx Sensor Heater Control Circuit/Open Bank 2
OBD-II Trouble Code Technical Description
NOx Sensor Heater Control Circuit/Open Bank 2
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) and typically applies to OBD-II vehicles. Vehicle makes may include but aren't limited to BMW, Dodge, Ram, Audi, Cummins, etc.
NOx (Nitrogen Oxide) sensors are primarily used for the emission systems in diesel engines. Their primary use is to detect NOx levels coming out of the exhaust after burning in the combustion chamber. The system then recycles these using different methods. Given the harsh environment of these sensors, they are composed of a combination of ceramic and a certain type of zirconia.
One of the downfalls of emitting NOx into the atmosphere is that it may cause smog and/or acid rain at times. Failure to sufficiently monitor and adjust NOx levels would result in a significant effect to the atmosphere around us and the air we breathe. The ECM (Engine control module) continuously monitors the NOx sensors to ensure acceptable emissions levels in your vehicle's exhaust. The NOx sensor heater control circuit is responsible for heating the sensor preemptively. It does this to expedite the sensor warm-up time, in turn bringing to operating temperature efficiently without solely relying on exhaust temperatures to warm itself up.
When it comes to P2218 and related codes, the NOx sensor heater control circuit malfunctioned somehow and the ECM has detected this. For reference sake, Bank 1 is on the side in which the number 1 cylinder is located. Bank 2 is on the other side. If your vehicle is a straight 6 or 4 cylinder, where there is only one head, it may be a two sided downpipe/ manifold. Always refer to your service manual for location designations as this will be integral in the diagnosing process.
P2218 is a generic trouble code that refers to "NOx Sensor Heater Control Circuit/Open Bank 2." It appears when the ECM detects an open or general malfunction within the NOx sensor heater control circuit on bank 2 .
Diesel engines especially produce a significant amount of heat so make sure to always let the system cool before working on any exhaust system components.
An example of NOx sensor (in this case, for GM vehicles):
What is the severity of this DTC?
Medium severity for this, as emission related faults really can effect the environment around this. That said, sometimes with emission faults, there will not be any symptoms present but can still have repercussions if left unattended.
What are some of the symptoms of the code?
Symptoms of a P2218 diagnostic code may include:
Failed emissions test Intermittent CEL (check engine light)What are some of the common causes of the code?
Causes for this P2218 cruise control code may include:
NOx sensor defective Heater in NOx sensor malfunctioning Internal open in ECM (Engine control module) or NOx sensor itself Water intrusion Broken connector tabs (intermittent connection) Melted harness Dirty sensor element High resistance present in heater control circuitWhat are some P2218 diagnostic and troubleshooting steps?
The first step in the troubleshooting process for any malfunction is to research the Technical Service Bulletins (TSB) for known issues with the specific vehicle.
Advanced diagnostic steps become very vehicle specific and may require the appropriate advanced equipment and knowledge to perform accurately. We include basic steps below but refer to a vehicle year/make/model/powertrain specific repair guide for specific steps for your vehicle.
Basic Step #1
Most NOx sensors used in diesel automotive and truck applications will be fairly accessible. Given that fact, keep in mind they can be extremely stubborn when removing with all the expanding and contracting that i
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