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DTC codes / P22xx · Fuel and air metering (injector circuits) / P2220

P2220NOx Sensor Heater Control Circuit High (Bank 2 Sensor 1)

P2220 indicates that the powertrain control module has detected an abnormally high current or voltage on the heater control circuit for the bank 2 sensor 1 nitrogen oxide (NOx) sensor. The NOx sensor heater is responsible for bringing the sensor element up to operating temperature quickly, and a high circuit condition means the control module sees more current or voltage than expected, which can prevent accurate NOx readings and may trigger the check engine light.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering (injector circuits)

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Reduced engine performance or limp mode in some vehicles as a protective measure
  • Increased fuel consumption due to altered fuel management strategies
  • Possible rough idle or hesitation if the fault affects closed-loop operation
  • Failed emissions test due to incomplete readiness monitors or increased NOx output
  • In rare cases, a burning smell or visible damage to the sensor wiring or connector

Common causes, most likely first

  1. Faulty NOx sensor heater element with an internal short to voltage or excessive current draw
  2. Damaged or chafed wiring in the heater control circuit, causing a short to power or ground
  3. Corroded, loose, or water-intruded connector at the NOx sensor or control module
  4. Failed heater control driver inside the powertrain control module
  5. Aftermarket or incorrect NOx sensor with incompatible heater resistance
  6. Exhaust system leaks or extreme temperatures damaging the sensor heater
  7. Poor ground connection for the sensor heater circuit

How to diagnose and fix it

  1. Connect a scan tool and record all stored codes, freeze-frame data, and NOx sensor heater circuit parameters to confirm P2220 is active and not a history code
  2. Visually inspect the NOx sensor wiring harness and connector for chafing, corrosion, or loose pins, and repair any obvious damage
  3. Measure the resistance of the NOx sensor heater element with a multimeter and compare it to the manufacturer's specification to identify an open or shorted heater
  4. Check the heater control circuit for a short to voltage or ground using a multimeter and wiring diagram, isolating the circuit from the control module if necessary
  5. Test the control module's heater driver output with a suitable load or oscilloscope to verify it can modulate the heater current correctly
  6. If the sensor heater resistance is out of specification or the circuit tests confirm a faulty sensor, replace the NOx sensor with an OEM-quality part
  7. Clear the codes, perform a road test to complete readiness monitors, and verify that P2220 does not return

What the NOx sensor heater code hides

  • A high circuit code often results from a shorted heater element inside the sensor, but a chafed wire harness rubbing against the exhaust or transmission can mimic the same fault and is frequently overlooked.
  • Some vehicles set P2220 when the NOx sensor heater current exceeds a threshold only during cold starts, so the fault may not appear during a warm-engine inspection.
  • Replacing the NOx sensor without checking the control module's heater driver can lead to repeat failures if the driver is damaged and continues to supply excessive current.
  • A weak or corroded ground for the heater circuit can cause the control module to see a high voltage drop, triggering P2220 even though the sensor itself is healthy.
  • P2220 is sometimes stored alongside glow plug or diesel particulate filter codes on diesel vehicles, and technicians may mistakenly focus on the aftertreatment system instead of the heater circuit.

Can I keep driving with P2220?

You can generally drive the vehicle with P2220, but avoid heavy loads and long periods of idling because the NOx sensor may not function correctly, leading to increased emissions and possible limp mode. Have the fault diagnosed soon to prevent secondary damage to the exhaust aftertreatment system.

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.

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