Open or damaged wiring in the NOx sensor heater circuit, including broken wires or corroded connectors; Failed NOx sensor heater element, which is internal to the sensor and not serviceable separately; Blown fuse or faulty relay that supplies power to the NOx sensor heater; Poor electrical connection at the sensor harness or at the control module; Corrosion or water intrusion in the connector causing high resistance; Rarely, a fault in the powertrain control module driver circuit for the heater

DTC codes / P22xx · Fuel and air metering (injector circuits) / P2218

P2218NOx Sensor Heater Control Circuit/Open (Bank 2 Sensor 1)

Q: What does code P2218 mean?

NOx Sensor Heater Control Circuit/Open (Bank 2 Sensor 1). P2218 indicates that the powertrain control module has detected an open circuit or excessive resistance in the heater circuit of the upstream nitrogen oxide (NOx) sensor on bank 2. The heater element is responsible for bringing the sensor up to operating temperature quickly, and when the circuit is open the sensor cannot function, triggering the malfunction indicator lamp.

P2218 indicates that the powertrain control module has detected an open circuit or excessive resistance in the heater circuit of the upstream nitrogen oxide (NOx) sensor on bank 2. The heater element is responsible for bringing the sensor up to operating temperature quickly, and when the circuit is open the sensor cannot function, triggering the malfunction indicator lamp.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine performance or power, particularly under load
Decreased fuel economy due to the system running in a default mode
Possible rough idle or hesitation if the fault affects closed-loop fueling
In some vehicles, a message on the driver information center indicating an emissions system fault
Failure to pass an emissions inspection due to the stored code

Common causes, most likely first

Open or damaged wiring in the NOx sensor heater circuit, including broken wires or corroded connectors
Failed NOx sensor heater element, which is internal to the sensor and not serviceable separately
Blown fuse or faulty relay that supplies power to the NOx sensor heater
Poor electrical connection at the sensor harness or at the control module
Corrosion or water intrusion in the connector causing high resistance
Rarely, a fault in the powertrain control module driver circuit for the heater

How to diagnose and fix it

Visually inspect the NOx sensor wiring and connector for damage, corrosion, or loose pins, and repair as needed
Check the fuse and relay that supply power to the NOx sensor heater circuit and replace if faulty
Measure the resistance of the NOx sensor heater element with a multimeter and compare to the manufacturer's specification
Perform a voltage drop test on the heater circuit to identify excessive resistance in the wiring
If the heater resistance is out of specification or the circuit is open internally, replace the NOx sensor
Clear the diagnostic trouble codes and verify the repair by running the appropriate monitor or test drive

What to check before replacing the NOx sensor

A blown fuse for the NOx sensor heater is a common cause that is often overlooked because the fuse may also power other circuits, leading to additional codes.
The heater circuit is separate from the sensor signal circuit, so a P2218 does not necessarily mean the sensor's measuring element is faulty, only its heater.
On many vehicles, the NOx sensor heater is controlled by the powertrain control module via a pulse-width modulated ground, so a simple voltage test at the connector may not reveal the fault.
Corrosion inside the connector can mimic a failed sensor, so always inspect and clean the terminals before condemning the sensor.
Bank 2 Sensor 1 refers to the upstream sensor on the bank of cylinders that does not contain cylinder 1, which can be confusing on V6 and V8 engines.

Can I keep driving with P2218?

The vehicle can generally be driven with this code, but the NOx sensor will not function, which may lead to increased emissions and reduced fuel economy. Avoid long-distance driving or heavy loads until the fault is repaired, and be aware that the vehicle may fail an emissions test.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.