Reductant Injector Circuit High (Bank 1 Unit 1)
The P2049 code means the vehicle's onboard diagnostic system has detected: Reductant Injector Circuit High (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)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Affiliate links — we earn a commission at no extra cost to you.
Common Symptoms
- Check Engine Light on
- DEF system warning active
- No DEF injection or overdosing
- Engine power limitation
- Speed limiter countdown on dashboard
Probable Causes (Ranked by Likelihood)
- Short to voltage in DEF injector wiring Very High
- Defective DEF injector High
- Open ground in injector circuit Moderate
- Heat-damaged wiring near exhaust Moderate
- PCM output driver malfunction Low
Frequently Asked Questions
What does P2049 mean?
P2049 means the DEF injector circuit is reading above the expected voltage, typically from a short to voltage in the wiring or a failed injector.
Can I drive with a P2049 code?
Drive only short distances. The DEF system cannot function correctly, and most vehicles will impose a speed limiter if not repaired.
How much does it cost to fix P2049?
Repairs typically cost $300 to $900 for injector replacement or wiring repair.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Confirm P2049 and review freeze frame data
-
Check DEF injector wiring for shorts to battery voltage
-
Verify injector ground circuit integrity
-
Test injector coil resistance and compare to OEM spec
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
P2049 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
- 2010-2016 Mercedes-Benz ML350 3.0L BlueTEC
- 2014-2020 Ram 3500 6.7L Cummins
- 2011-2017 Ford F-350 6.7L Power Stroke
- 2012-2019 Chevrolet Silverado 3500 6.6L Duramax
Related Codes
Explore More
Was this helpful?
Send this to whoever is fixing the car — your mechanic, or the person asking what the light means.