Open or high-resistance heater element inside the NOx sensor itself; Damaged, chafed, or corroded wiring between the NOx sensor heater circuit and the engine control module; Loose or contaminated electrical connector at the NOx sensor or at the control module; Blown fuse or faulty relay that supplies power to the NOx sensor heater circuit; Engine control module driver circuit fault for the NOx sensor heater; Poor ground connection shared by the NOx sensor heater circuit; Aftermarket or incorrect NOx sensor with a heater element that does not meet the original resistance specification

DTC codes / P22xx · Fuel and air metering (injector circuits) / P2206

P2206NOx Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

Q: What does code P2206 mean?

NOx Sensor Heater Control Circuit Low (Bank 1 Sensor 1). P2206 means the engine computer has detected that the heater circuit inside the nitrogen oxide (NOx) sensor at bank 1 sensor 1 is drawing too little current or has an abnormally low voltage on its control wire. The sensor's heater is responsible for bringing the sensing element up to operating temperature quickly, so a low circuit condition prevents the sensor from reporting accurate NOx levels and can affect emissions and engine management.

P2206 means the engine computer has detected that the heater circuit inside the nitrogen oxide (NOx) sensor at bank 1 sensor 1 is drawing too little current or has an abnormally low voltage on its control wire. The sensor's heater is responsible for bringing the sensing element up to operating temperature quickly, so a low circuit condition prevents the sensor from reporting accurate NOx levels and can affect emissions and engine management.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Reduced fuel economy or slightly rough running if the engine computer limits certain strategies
A pending or stored emissions-related fault that may prevent passing an inspection
In some vehicles, a message in the driver information center about an emissions system fault
Intermittent warning light if the low circuit condition is caused by a loose or corroded connection
Possible limp-home or reduced power mode on vehicles that closely monitor NOx sensor performance

Common causes, most likely first

Open or high-resistance heater element inside the NOx sensor itself
Damaged, chafed, or corroded wiring between the NOx sensor heater circuit and the engine control module
Loose or contaminated electrical connector at the NOx sensor or at the control module
Blown fuse or faulty relay that supplies power to the NOx sensor heater circuit
Engine control module driver circuit fault for the NOx sensor heater
Poor ground connection shared by the NOx sensor heater circuit
Aftermarket or incorrect NOx sensor with a heater element that does not meet the original resistance specification

How to diagnose and fix it

Check for any related technical service bulletins or known wiring concerns for the vehicle before beginning diagnosis
Inspect the NOx sensor connector and the control module connector for corrosion, loose pins, or pushed-out terminals
Measure the resistance of the NOx sensor heater element at the sensor connector and compare it to the manufacturer's specification
Check the heater circuit fuse and relay, and verify that battery voltage is present at the heater supply wire with the key on
Perform a voltage drop test on the heater ground circuit and on the control wire from the sensor to the engine control module
If the wiring and supply are good, command the heater on with a scan tool and measure current draw to confirm whether the sensor or the control module is at fault
Replace the NOx sensor only after confirming the heater element is open or out of specification, then clear codes and verify the repair with a road test

What a low NOx heater circuit really means

A low circuit code does not automatically mean the NOx sensor is bad; a corroded connector or a chafed wire often causes the same low-current reading and costs far less to fix.
The heater element inside a NOx sensor can fail open while the sensor still reports plausible-looking data at times, so resistance testing at the connector is more reliable than trusting live data alone.
Some vehicles set P2206 when the heater supply fuse is shared with other emissions components, so a blown fuse may also disable the secondary air pump or other circuits and produce additional codes.
Technicians sometimes replace the NOx sensor only to have the code return because the engine control module heater driver was damaged by a shorted sensor heater, so the control wire should be checked for continuity to ground before installing a new sensor.
On vehicles with two NOx sensors, bank 1 sensor 1 is usually the upstream sensor, and swapping sensors to see if the code moves is a valid diagnostic step only when the connectors and thread types are identical.

Can I keep driving with P2206?

The vehicle is generally safe to drive with P2206 because the fault affects emissions control rather than immediate engine operation, but avoid long periods of heavy load or towing until it is repaired. Have the circuit inspected soon, since continued driving with a failed NOx sensor heater can lead to increased emissions and may cause the vehicle to fail an emissions inspection.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.