P249E on GMC
Diesel Particulate Filter Pressure Sensor Intermittent/Erratic (Bank 1)
P249E on GMC vehicles indicates diesel particulate filter pressure sensor intermittent/erratic (bank 1). Au7o has documented this code across 1 GMC model — most commonly on Sierra 3500HD. Despite the label sometimes seen, the standard SAE definition of P249E is 'Closed Loop Reductant Injection Control At Limit – Flow Too High,' a diesel emissions code in the Selective Catalytic Reduction (SCR) system. The SCR system injects diesel exhaust fluid (DEF/AdBlue) into the exhaust to neutralize nitrogen oxides, and the engine computer adjusts the dosing in a closed loop using NOx sensors. This code sets when the system has to push DEF flow to its maximum correction limit to keep emissions in range, signaling the injection control can no longer compensate. It generally indicates a DEF delivery, fluid-quality, or sensor problem rather than a quick fix, and can lead to reduced power or warning countdowns if ignored. Typical repair costs on GMC range from $300 to $2,000, depending on the specific model and root cause.
Common Causes of P249E
- •Contaminated, diluted, or incorrect DEF/AdBlue fluid
- •Clogged or failing DEF injector/dosing valve
- •Faulty NOx sensor (upstream or downstream)
- •Degraded or failed SCR catalyst
- •DEF line/tank leak or pump pressure fault
- •Exhaust leak upstream of the SCR system
- •Wiring or connector faults in the dosing/sensor circuits
P249E on GMC by Model
GMC Sierra 3500HD(1 issue)
- Diesel Exhaust Fluid (DEF) System Failures2011-2020
The Duramax diesel Sierra 3500HD (2011+) equipped with the DEF/SCR emission system develops failures in the DEF tank heater, DEF quality sensor, and associated wiring. Wires to the DEF tank short out, and because they share a harness with the transmission, this can trigger both DEF and transmission warnings simultaneously. Cold weather operation exacerbates DEF system problems as the fluid crystallizes.
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What does P249E mean on GMC?▼
P249E stands for "Diesel Particulate Filter Pressure Sensor Intermittent/Erratic (Bank 1)." Despite the label sometimes seen, the standard SAE definition of P249E is 'Closed Loop Reductant Injection Control At Limit – Flow Too High,' a diesel emissions code in the Selective Catalytic Reduction (SCR) system. The SCR system injects diesel exhaust fluid (DEF/AdBlue) into the exhaust to neutralize nitrogen oxides, and the engine computer adjusts the dosing in a closed loop using NOx sensors. This code sets when the system has to push DEF flow to its maximum correction limit to keep emissions in range, signaling the injection control can no longer compensate. It generally indicates a DEF delivery, fluid-quality, or sensor problem rather than a quick fix, and can lead to reduced power or warning countdowns if ignored. On GMC specifically, this code is documented across 1 model.
What causes P249E on GMC vehicles?▼
Common causes on GMC: Contaminated, diluted, or incorrect DEF/AdBlue fluid, Clogged or failing DEF injector/dosing valve, Faulty NOx sensor (upstream or downstream), Degraded or failed SCR catalyst, DEF line/tank leak or pump pressure fault. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P249E on a GMC?▼
Repair costs on GMC range from $300 to $2,000, depending on the specific model and root cause.
Which GMC models have P249E documented?▼
Au7o has documented P249E on 1 GMC model: Sierra 3500HD.