P2207

Code

Generic P — Powertrain

NOx Sensor Heater Control Circuit High Bank 1 Sensor 1

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 37 RU: 27

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Page language: EN

Causes

Short to battery voltage on the NOx heater control circuit
Failed NOx sensor heater element (internal short)
Damaged/shorted wiring or pins at the sensor connector
Corroded or loose connector causing abnormal voltage readings
Faulty heater relay or fuse supplying constant voltage
Defective PCM/ECM heater driver output

Symptoms

Malfunction indicator lamp (MIL) illuminated
Stored P2207 trouble code (possibly with other NOx heater codes)
Possible reduced emissions control performance or failed emissions test
NOx sensor not reaching operating temperature (may affect regen or SCR control)

What to check

Read freeze frame and related codes; note conditions when code set
Visual inspection of sensor, connector, wiring harness, and mounting for damage or corrosion
Check relevant fuses and relays for the NOx heater circuit
Back-probe harness with ignition on to measure voltage at heater supply and control pins
Measure heater element resistance (with sensor disconnected) and compare to spec
Wiggle test wiring and observe live data/voltage for intermittent faults

Signal parameters

Heater supply voltage: typically battery voltage (~12 V) when circuit is powered
Heater control output: PWM or switched output from PCM — expected to vary with engine/ambient conditions
Heater element resistance: typically low (ohms to tens of ohms); an open or near-zero short is a fault
When PCM commands heater off, control circuit should not be stuck at battery voltage

Diagnostic algorithm

Retrieve freeze frame and related NOx/heater codes. Note ignition state, engine temp, and voltage when set.
Perform a visual inspection of Bank 1 Sensor 1 harness and connector for damage, corrosion, pin push-out, or aftermarket splices. Repair as needed.
Check fuses/relays for the heater circuit. Replace any blown fuses or faulty relays and retest.
With ignition off, disconnect the NOx sensor. Measure heater element resistance across the heater pins. If open/infinite or shorted to ground/power, replace the sensor.
With ignition ON (engine off), back-probe the harness connector: measure voltage on the heater supply and the control circuit. Compare to battery voltage and expected control behavior. If harness shows battery voltage when PCM should be sinking or low, suspect a short to power in the harness or stuck relay.
Check for short to battery by disconnecting wiring and measuring for continuity to battery positive. Repair wiring if short found.
If wiring and sensor check good, command the heater ON/OFF with a scan tool and observe voltages/duty cycle. If PCM is commanding but output remains high or does not change, suspect PCM/ECM driver fault.
After repairs, clear codes and perform road/drive cycle to confirm code does not return. If intermittent, perform wiggle/stress tests to reproduce.

Likely causes

Wiring shorted to battery (harness pin contacting +12V)
Internal sensor heater fault (shorted heater element)
Connector corrosion or terminal push-out causing contact with power
Failed PCM driver stage (stuck high output)

Fault status

⚠️ Status

NOx Sensor Heater Control Circuit High - Bank 1 Sensor 1. Heater circuit voltage higher than expected; possible short to voltage, sensor or PCM driver fault. MIL illuminated.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours