P2211

Code

Generic P — Powertrain

NOx Sensor Heater Sense Circuit High Bank 1 Sensor 1

Brand: Generic

Type: P — Powertrain

Views: UK: 22 EN: 46 RU: 37

AI status

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Page language: EN

Causes

Short to battery/ignition voltage in the heater sense circuit
Failed NOx sensor heater element or internal sensing circuit
Open or damaged wiring in heater or sense circuit
Poor or corroded connector pin or terminal at the sensor or ECU/PCM
Faulty fuse, relay, or power supply feeding the heater circuit
PCM or ECU internal fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced emissions system performance or disabled NOx control functions
Possible difficulty with DPF or SCR regeneration (diesel applications)
Extended warm-up time for emission system components
Vehicle may enter limited-emissions limp mode on some vehicles

What to check

Read freeze frame and live data with a scan tool; note voltage/temperature values for Bank 1 Sensor 1 heater and sense circuits
Inspect sensor connector and wiring for corrosion, damage, heat exposure, or loose terminals
Check relevant fuses and relays supplying heater power
Perform wiggle test on wiring harness while monitoring live data for voltage changes
Backprobe heater power and heater sense pins at the sensor with key ON and engine OFF, then with engine running if safe
Measure heater element resistance at the sensor (unplugged) per service info

Signal parameters

Heater supply voltage (typical): ~12 V (battery voltage) when heater relay/power is commanded ON — varies by vehicle
Heater sense voltage (expected): normally low when circuit is healthy; a ‘high’ fault often means sense voltage near battery voltage or above threshold (many systems flag >4–5 V as high)
Heater resistance (typical range): varies with sensor design (commonly a few ohms to a few tens of ohms) — refer to manufacturer spec
PCM command status: heater ON/OFF from PCM (verify command present when expected)

Diagnostic algorithm

Retrieve freeze frame and full readout of related data and any other codes. Clear codes and attempt a drive cycle to confirm repeat.
Visually inspect Bank 1 Sensor 1 connector, wiring, and nearby components for heat damage, chafing, corrosion, or rodent damage. Repair any obvious damage.
Check fuses and relays that supply heater power; replace if faulty.
With ignition ON (engine OFF) backprobe sensor connector: measure heater power supply pin for battery voltage and heater sense pin voltage. Record values.
Command heater ON with a scan tool (if available) and observe changes in sense voltage and heater current. If sense measures near battery voltage with heater commanded off or on, suspect short to voltage or open sense return.
Disconnect sensor and measure heater element resistance. Compare to spec. Very high/OL suggests open heater; very low suggests shorted element.
With sensor disconnected, check sense circuit for short to battery by measuring voltage at the harness side. Also check continuity from sense to PCM and for short to power or other circuits.
Repair wiring or connector faults or replace the NOx sensor if the heater element or internal circuitry is out of spec. If wiring and sensor are good and fault persists, test/replace PCM as a last resort.
After repair, clear codes and verify proper operation through a drive cycle and live data monitoring.

Likely causes

Connector corrosion or bent pin at Bank 1 Sensor 1
Damaged wiring chafed and shorting to a power source
Failed NOx sensor heater or internal electronics
Blown/shorted heater control fuse or stuck relay
PCM input with internal short (less common)

Fault status

⚠️ Status

NOx sensor heater sense circuit voltage high on Bank 1 Sensor 1 — heater circuit sensing a voltage above expected threshold (possible short to battery, open/failed sensor, or wiring fault).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours