P2205

Code

Generic P — Powertrain

NOx Sensor Heater Control Circuit/Open Bank 1 Sensor 1

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 86 RU: 29

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Page language: EN

Causes

Open circuit in NOx sensor heater wiring (broken wire, connector open)
Corroded or loose connector terminals at the NOx sensor
Blown fuse or failed relay feeding the heater circuit
Failed NOx sensor heater element
Poor ground or high resistance in ground circuit
ECU/PCM heater driver output fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Failed emissions test or elevated NOx emissions
Reduced engine/aftertreatment performance or delayed DPF/regen behavior on vehicles with SCR systems
Possible limp-home mode on some vehicles
Poor fuel economy in some conditions (indirect)

What to check

Read freeze frame and live data with a scan tool; confirm P2205 and related codes
Visually inspect sensor, connector, and wiring harness at Bank 1 Sensor 1 for damage, corrosion, or disconnection
Check related fuses and relays supplying the NOx heater circuit
Wiggle test wiring while monitoring code or heater status to spot intermittent opens
Measure resistance of heater element at the sensor connector with connector unplugged
Measure supply voltage at heater connector with ignition on (engine off)

Signal parameters

Expected heater supply voltage: ~11–14.5 V with ignition ON (vehicle battery voltage)
Typical heater resistance: often in the low ohms to tens of ohms range (commonly ~1–20 Ω depending on sensor) — consult vehicle-specific spec
Heater current: varies by design (approx. 0.5–5 A typical)
Open-circuit reading: infinite resistance / OL when heater element is failed or wiring open

Diagnostic algorithm

Verify the active fault and review freeze-frame data with a scan tool; note any related NOx or heater codes.
Visually inspect Bank 1 Sensor 1 harness, connector, and sensor for damage, corrosion, or contamination. Repair or clean as needed.
Check fuses/relays in the NOx heater feed circuit; replace any blown fuses and retest.
With ignition OFF, disconnect the NOx sensor connector. Measure heater element resistance across heater pins; compare to spec. If OL or out of range, suspect sensor heater failure and consider replacing sensor.
With ignition ON (engine OFF), measure voltage at the heater feed terminal of the sensor connector to confirm supply presence. If no supply, trace back to fuse/relay/ECU.
Check ground continuity from the sensor ground terminal to chassis/ECU ground. Repair any high-resistance grounds.
If supply and ground are present and heater resistance is correct but code persists, back-probe and observe heater circuit while commanding heater ON (if vehicle supports) or while engine running to look for intermittent faults.
If wiring and sensor are good, test or bench-check ECU heater driver output per factory procedures; replace ECU only after confirming driver failure.
Clear codes and perform test drive/regeneration cycle to verify repair.

Likely causes

Broken or disconnected heater feed wire at sensor harness
Corrosion or water intrusion at sensor connector causing an open connection
Blown heater fuse or defective heater relay
Internal heater element failure inside the NOx sensor
Damaged/crushed harness between sensor and ECU
Failed ECU driver transistor for the heater circuit

Fault status

⚠️ Status

P2205 — NOx Sensor Heater Control Circuit/Open Bank 1 Sensor 1. The ECU detected an open or fault in the heater circuit for the upstream NOx sensor on bank 1; heater not reaching expected operation.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours