P2203 on Chevrolet
NOx Sensor Circuit High (Bank 1)
P2203 on Chevrolet vehicles indicates nox sensor circuit high (bank 1). Au7o has documented this code across 1 Chevrolet model — most commonly on Silverado 2500HD. Generic code. The module detects a voltage in the Bank 1 NOx sensor circuit that is above the normal operating range. A persistently high signal usually indicates a short to voltage, an open in the circuit pulling the reading high, or an internal sensor fault. Typical repair costs on Chevrolet range from $400 to $1,400, depending on the specific model and root cause.
Common Causes of P2203
- •Signal wire shorted to a voltage source
- •Open circuit causing the input to float high
- •Failed NOx sensor / sensor control module
- •Corroded or damaged connector
- •Wiring damage from heat or chafing near the exhaust
P2203 on Chevrolet by Model
Chevrolet Silverado 2500HD(1 issue)
- LML Duramax NOx Sensor Drift - False 'DEF Quality Poor' Warning and Speed Limiter Countdown2011-2015
Early LML trucks (roughly 2011 through 2014) are documented for upstream and downstream NOx sensors that drift out of calibration rather than fail outright. The SCR system compares the two sensors to judge DEF effectiveness; when a sensor reads out of range the truck posts 'DEF Quality Poor' or 'Exhaust Fluid System - See Dealer' and begins a countdown that ultimately limits the truck to a 4 mph creep speed - with perfectly good DEF in the tank. Because the sensors drift in and out of range, the message often comes and goes, which is why owners replace sensors and see the light return. GM has published harness-chafe bulletins covering the same fault codes, so the wiring is a genuine root cause and not just a sensor problem.
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View P2203 across all makes →Frequently Asked Questions
What does P2203 mean on Chevrolet?▼
P2203 stands for "NOx Sensor Circuit High (Bank 1)." Generic code. The module detects a voltage in the Bank 1 NOx sensor circuit that is above the normal operating range. A persistently high signal usually indicates a short to voltage, an open in the circuit pulling the reading high, or an internal sensor fault. On Chevrolet specifically, this code is documented across 1 model.
What causes P2203 on Chevrolet vehicles?▼
Common causes on Chevrolet: Signal wire shorted to a voltage source, Open circuit causing the input to float high, Failed NOx sensor / sensor control module, Corroded or damaged connector, Wiring damage from heat or chafing near the exhaust. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P2203 on a Chevrolet?▼
Repair costs on Chevrolet range from $400 to $1,400, depending on the specific model and root cause.
Which Chevrolet models have P2203 documented?▼
Au7o has documented P2203 on 1 Chevrolet model: Silverado 2500HD.