P2218

Code

Generic P — Powertrain

NOx Sensor Heater Control Circuit/Open Bank 2

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 35 RU: 31

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Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
Reduced or altered diesel aftertreatment operation (increased regen frequency or inhibited regen)
Failed emissions test / increased NOx emissions
Possible reduced fuel economy or limp/limited-emissions mode on some vehicles
Stored freeze-frame data and related NOx/aftertreatment faults

Retrieve and record freeze-frame data and live PIDs with a scan tool (heater command/status, sensor temperature, NOx sensor messages)
Visual inspection of Bank 2 NOx sensor connector and wiring for damage, corrosion, or disconnection
Check fuses and relays related to exhaust aftertreatment/heater circuits
Backprobe the sensor connector while commanding the heater ON from a scan tool and observe supply and control signals
Measure resistance of the NOx sensor heater element with the sensor disconnected (compare to specification)
Perform continuity test between sensor connector and ECM pins for power, control and ground

Heater supply voltage (with heater commanded ON): ~11–14 V (battery voltage minus small drop)
Heater element resistance (typical): commonly 2–30 Ω depending on manufacturer — check OEM spec
Heater current when commanded: often 0.5–5 A depending on sensor design
Control circuit behavior: ECM usually provides a switched ground or PWM; expected to toggle when heater is commanded

Read freeze-frame and all stored codes. Note related aftertreatment or NOx codes. 2) Visually inspect the Bank 2 NOx sensor, its connector, and wiring for damage, corrosion, or disconnection. Repair obvious problems. 3) Check relevant fuses/relays; replace if blown or faulty. 4) With ignition ON (engine OFF) and using a scan tool, command the NOx heater ON and monitor heater status and supply PID. Verify heater command is present. 5) Backprobe the sensor connector: verify heater supply voltage (should be ≈ battery voltage when commanded) and control/ground signal from ECM. 6) Turn ignition OFF, unplug sensor, and measure heater element resistance across heater pins. Compare to OEM spec; an open or very high resistance indicates bad sensor. 7) Check continuity from the sensor harness pins to the ECM connector for open/high resistance and check for shorts to ground or battery. Repair wiring faults or corroded connectors. 8) If wiring and connectors are good but measurements indicate abnormal control signals or intermittent operation, consider ECM heater driver fault — confirm with manufacturer procedures before replacing ECM. 9) After repairs or sensor replacement, clear codes, perform readiness/regen cycle or short road test, and verify code does not return.
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