NOx Sensor Heater Circuit Low (Bank 1)
The P2206 code means the vehicle's onboard diagnostic system has detected: NOx Sensor Heater Circuit Low (Bank 1). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- $250 - $800 (parts and labor)
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What Are the Symptoms of P2206?
- Check Engine Light on
- Prolonged sensor warm-up time
- Cold start emissions issues
- Possible reduced power mode
- Failed emissions test
What Causes P2206? (Most Likely First)
- Open circuit in the NOx sensor heater wiring Very High
- Failed heater element inside the NOx sensor High
- Corroded heater circuit connector Moderate
- Poor ground connection for the heater Moderate
- ECM heater control driver failure Low
Can I Still Drive with P2206?
Yes, but fix soon. P2206 is rated moderate severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
Frequently Asked Questions
What does heater circuit low mean?
It means the current flow through the NOx sensor heater circuit is below the expected minimum, typically caused by an open circuit, bad connection, or failed heater element.
Can I test the NOx sensor heater with a multimeter?
Yes, you can measure the heater element resistance at the sensor connector. A typical reading is 2 to 10 ohms depending on the manufacturer. An open (infinite) reading means the heater has failed.
Is the heater element replaceable separately?
No, the heater is built into the NOx sensor assembly. If the heater fails, the entire sensor must be replaced.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P2206?
-
Measure voltage at the NOx sensor heater connector with key on -- should have battery voltage
-
Check heater ground circuit for continuity back to the ECM
-
Measure heater element resistance -- an open reading indicates a failed heater
-
Inspect connectors for corrosion or backed-out pins
-
Replace the NOx sensor if the internal heater has failed
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Which Vehicles Commonly Get P2206?
- 2012-2019 Mercedes-Benz ML350 BlueTEC
- 2013-2020 BMW 535d
- 2014-2020 Ram 3500 Cummins
- 2015-2020 Ford F-250 Power Stroke
- 2011-2019 Audi Q7 TDI
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