P249D on Chevrolet
Closed Loop Reductant Injection Control At Limit - Flow Too Low
P249D on Chevrolet vehicles indicates closed loop reductant injection control at limit - flow too low. Au7o has documented this code across 1 Chevrolet model — most commonly on Equinox. Generic diesel SCR code indicating the closed-loop reductant (DEF) injection control has reached its adjustment limit because DEF flow is too low. The PCM is commanding more DEF than the system can deliver, so NOx cannot be adequately reduced. Typical repair costs on Chevrolet range from $350 to $1,500, depending on the specific model and root cause.
Common Causes of P249D
- •Clogged or restricted DEF injector
- •Weak DEF supply/metering pump
- •Restricted DEF lines or filter
- •Low DEF level or poor DEF quality
- •Failing NOx sensor skewing the feedback loop
P249D on Chevrolet by Model
Chevrolet Equinox(1 issue)
- 1.6L Diesel NOx Sensor Failure / DEF System Faults Causing Reduced Power and Limp Mode2018-2019
The diesel Equinox (1.6L LH7) is prone to NOx-sensor and diesel-exhaust-fluid (DEF/SCR) emissions faults. Failing or out-of-calibration NOx sensors and reductant-injection problems set codes such as P11DB (NOx sensor 1 performance) and P249D (closed-loop reductant control at limit), trigger a 'service emissions system' warning with a countdown, and ultimately force the vehicle into a speed-limited limp mode to protect the SCR catalyst. Owners report repeat failures because GM revised the NOx sensors multiple times. A holed/leaking charge-air cooler can also let unmetered air in and mimic the same emissions faults, so the intake must be checked too. This is a high-stakes, expensive emissions issue for the relatively rare but enthusiast-tracked diesel.
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View P249D across all makes →Frequently Asked Questions
What does P249D mean on Chevrolet?▼
P249D stands for "Closed Loop Reductant Injection Control At Limit - Flow Too Low." Generic diesel SCR code indicating the closed-loop reductant (DEF) injection control has reached its adjustment limit because DEF flow is too low. The PCM is commanding more DEF than the system can deliver, so NOx cannot be adequately reduced. On Chevrolet specifically, this code is documented across 1 model.
What causes P249D on Chevrolet vehicles?▼
Common causes on Chevrolet: Clogged or restricted DEF injector, Weak DEF supply/metering pump, Restricted DEF lines or filter, Low DEF level or poor DEF quality, Failing NOx sensor skewing the feedback loop. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P249D on a Chevrolet?▼
Repair costs on Chevrolet range from $350 to $1,500, depending on the specific model and root cause.
Which Chevrolet models have P249D documented?▼
Au7o has documented P249D on 1 Chevrolet model: Equinox.