P229E on 2015-2020 Mercedes-Benz V-Class (V200 d, V220 d, V250 d) — NOx Sensor Circuit (Bank 1 Sensor 2)
1 vehicles · 1 makes · $300-$900 repair
Most Reported On
P229E is an OBD-II diagnostic trouble code meaning “NOx Sensor Circuit (Bank 1 Sensor 2).” P229E indicates a fault in the NOx (nitrogen oxide) sensor circuit for Bank 1 Sensor 2, which monitors the nitrogen oxide content in the exhaust gas, typically downstream in the SCR/aftertreatment system on diesel engines. It sets when the engine control module detects an electrical problem (open, short, or implausible signal) in this sensor circuit. The vehicle may enter a reduced-power "derate" mode to limit emissions until the fault is repaired. Note: some manufacturers reassign this code (e.g., RAM uses it for a seat back heater sensor, VW for a seatbelt load limiter), so verify against the specific make. This code is most commonly reported on 2015-2020 Mercedes-Benz V-Class (V200 d, V220 d, V250 d), with repair costs ranging from $300 to $900.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P229E, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
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- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
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- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
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- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
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- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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FAQ
What does P229E mean?
P229E stands for "NOx Sensor Circuit (Bank 1 Sensor 2)." P229E indicates a fault in the NOx (nitrogen oxide) sensor circuit for Bank 1 Sensor 2, which monitors the nitrogen oxide content in the exhaust gas, typically downstream in the SCR/aftertreatment system on diesel engines. It sets when the engine control module detects an electrical problem (open, short, or implausible signal) in this sensor circuit. The vehicle may enter a reduced-power "derate" mode to limit emissions until the fault is repaired. Note: some manufacturers reassign this code (e.g., RAM uses it for a seat back heater sensor, VW for a seatbelt load limiter), so verify against the specific make.
What are the most common causes of P229E?
The most common causes of P229E are: Failed or contaminated downstream NOx sensor (Bank 1 Sensor 2), Damaged, corroded, or loose NOx sensor wiring or connector, Open or short circuit in the NOx sensor harness, Faulty NOx sensor control module, Exhaust leak near the sensor affecting readings, Problem in the SCR/DEF aftertreatment system causing implausible NOx values. The specific cause varies by vehicle.
How much does it cost to fix P229E?
Repair costs for P229E range from $300 to $900, depending on the vehicle and root cause.
Which vehicles are affected by P229E?
Au7o has documented P229E across 1 vehicle models from 1 manufacturers: Mercedes-Benz.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.