P2218: NOx Sensor Heater Control Circuit/Open Bank 2
What to do
The car drives normally and the inducement countdown applies. Worth knowing that short journeys shorten the life of these sensors, because the exhaust never dries out and the heater has to work around condensation on every start — an occasional longer run is genuinely kinder to the emissions system.
What this code means
A fault in the circuit driving the bank 2 NOx sensor's heater. Without the heater there is no measurement at all — the ceramic element only conducts at high temperature, so a cold sensor is blind rather than inaccurate. The full explanation, including why the heater is deliberately delayed after a cold start and why short journeys are hard on these sensors, is at P2205.
Likely causes
Start here
- Faulty NOx sensor · moderate
- Open circuit in heater wiring · moderate
- Corroded or loose connector · easy
Less common
- Blown fuse or failed supply · easy
- Thermal shock damage from exhaust condensation · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
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