Reductant Injector Circuit Low (Bank 1 Unit 1)
The P2048 code means the vehicle's onboard diagnostic system has detected: Reductant Injector Circuit Low (Bank 1 Unit 1). This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $300 - $900 (parts and labor)
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Common Symptoms
- Check Engine Light illuminated
- DEF system fault warning
- SCR system not functioning
- Engine power may be reduced
- Possible speed limiter activation
Probable Causes (Ranked by Likelihood)
- Short to ground in DEF injector circuit Very High
- Failed DEF injector coil High
- Water intrusion in injector connector Moderate
- Damaged wiring shorted to chassis Moderate
- PCM driver circuit fault Low
Frequently Asked Questions
What does P2048 mean?
P2048 indicates the DEF injector circuit has a low voltage condition, usually from a short to ground in the wiring or a failed injector coil.
Can I drive with a P2048 code?
Short-distance driving only. The SCR system is not functioning, and a speed limiter may be activated on many modern diesel vehicles.
How much does it cost to fix P2048?
Expect $300 to $900 for DEF injector replacement or wiring repair.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read freeze frame data for P2048
-
Inspect DEF injector connector for water damage
-
Measure injector circuit for shorts to ground
-
Test injector coil resistance
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
P2048 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- 2012-2018 BMW 328d 2.0L Diesel
- 2010-2016 Mercedes-Benz ML350 3.0L BlueTEC
- 2014-2020 Ram 3500 6.7L Cummins
- 2011-2017 Ford F-350 6.7L Power Stroke
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