P2201 on Mercedes-Benz
NOx Sensor Circuit Range/Performance (Bank 1)
P2201 on Mercedes-Benz vehicles indicates nox sensor circuit range/performance (bank 1). Au7o has documented this code across 1 Mercedes-Benz model — most commonly on E-Class. This code means the engine computer detected that the NOx (nitrogen oxides) sensor signal on Bank 1 is out of its expected range or not performing correctly. The NOx sensor measures nitrogen oxide levels in the exhaust, mainly on diesel and lean-burn engines, to manage the emissions/SCR system. An implausible reading means the computer can't accurately monitor or control emissions. While not an immediate driving hazard, it can cause emissions faults, failed inspections, and in some vehicles reduced-power modes if the system can't verify proper operation. Typical repair costs on Mercedes-Benz range from $600 to $1,800, depending on the specific model and root cause.
Common Causes of P2201
- •Faulty NOx sensor
- •Wiring or connector problems at the NOx sensor
- •Exhaust leak near the sensor affecting readings
- •Contaminated or aged sensor element
- •DEF/SCR system performance issues skewing readings
- •NOx sensor control module fault
P2201 on Mercedes-Benz by Model
Mercedes-Benz E-Class(1 issue)
- NOx Sensor Failure in the SCR/AdBlue System Triggering a Start-Prevention Countdown2011-2016
BlueTEC diesels use a selective catalytic reduction system that injects AdBlue urea into the exhaust, with NOx sensors upstream and downstream of the SCR catalyst reporting how effectively NOx is being converted. The downstream sensor in particular lives in a harsh, hot, urea-crystallizing environment and degrades or fails outright. When the ECU cannot confirm emissions compliance, US-market emissions law forces the car into a start-prevention strategy: the cluster begins displaying a remaining-starts or remaining-distance countdown, and when it reaches zero the engine will not restart at all. Owners describe the countdown appearing with a full AdBlue tank and no obvious driveability problem, which makes the fault feel arbitrary and is why it generates so much forum traffic. The countdown does not pause simply because the car is parked, so a car left with a low count can become undriveable in the owner's driveway.
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View P2201 across all makes →Frequently Asked Questions
What does P2201 mean on Mercedes-Benz?▼
P2201 stands for "NOx Sensor Circuit Range/Performance (Bank 1)." This code means the engine computer detected that the NOx (nitrogen oxides) sensor signal on Bank 1 is out of its expected range or not performing correctly. The NOx sensor measures nitrogen oxide levels in the exhaust, mainly on diesel and lean-burn engines, to manage the emissions/SCR system. An implausible reading means the computer can't accurately monitor or control emissions. While not an immediate driving hazard, it can cause emissions faults, failed inspections, and in some vehicles reduced-power modes if the system can't verify proper operation. On Mercedes-Benz specifically, this code is documented across 1 model.
What causes P2201 on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: Faulty NOx sensor, Wiring or connector problems at the NOx sensor, Exhaust leak near the sensor affecting readings, Contaminated or aged sensor element, DEF/SCR system performance issues skewing readings. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2201 on a Mercedes-Benz?▼
Repair costs on Mercedes-Benz range from $600 to $1,800, depending on the specific model and root cause.
Which Mercedes-Benz models have P2201 documented?▼
Au7o has documented P2201 on 1 Mercedes-Benz model: E-Class.