O2 Sensor Circuit Range/Performance Bank 1 Sensor 1
The DURAMAX-P2A00 (Duramax) diesel fault code means: O2 Sensor Circuit Range/Performance Bank 1 Sensor 1. This is a moderate severity code.
Unverified. We could not confirm this code's definition against freely available manufacturer documentation, so treat the meaning, severity and fix guidance on this page as unconfirmed. Check it against the manufacturer's service information for your exact model and serial range before acting on it. This page is kept out of search engines for that reason, and we are working through this family manual by manual.
- Keep driving?
- Yes, with caution
- DIY difficulty
- advanced
- Estimated cost
- $300-$500 NOx sensor, $200 DEF injector, $2,500-$4,500 full SCR replacement
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View pilot availability →What Are the Symptoms of DURAMAX-P2A00?
- Check Engine Light
- 'Service Emissions System' or 'Service DEF System' message
- Countdown to speed limit reduction (5 mph eventually) if uncorrected
- Extra DEF consumption
- DPF regen occurring more frequently
What Causes DURAMAX-P2A00? (Most Likely First)
- Upstream O2 sensor aging Very Likely
- Contaminated DEF fluid (use ONLY API-certified DEF) Likely
- DEF injector clogged with crystallized urea Possible
- NOx sensor end-of-life (typical 100-150K miles) Possible
- Wiring or connector fault at sensor Possible
Can I Still Drive with DURAMAX-P2A00?
Yes, with caution. DURAMAX-P2A00 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What is P2A00 on a Duramax?
Duramax code P2A00 (O2 Sensor Circuit Range/Performance Bank 1 Sensor 1) is a moderate-severity diagnostic trouble code triggered by the engine control module when it detects a problem in the associated system. ALWAYS use API-certified DEF from a sealed container. Contaminated or wrong DEF is the #1 cause of SCR system failure.
Is a Duramax P2A00 safe to drive?
Short-term yes, but the PCM enters a countdown that reduces top speed to 5 mph if the fault isn't cleared. Repair before hitting 0 miles remaining.
How much does it cost to fix P2A00 on a Duramax?
NOx sensor $300-$500 installed. DEF injector $200-$400. SCR catalyst $2,500-$4,500.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose DURAMAX-P2A00?
Scan for all SCR codes together — a single NOx sensor failure often cascades into multiple DTCs
Verify DEF quality — use a refractometer or DEF test strips (should be 32.5% urea ± 0.5%)
Inspect the DEF injector for crystallized urea deposits; clean or replace
If both upstream and downstream NOx sensors are reading the same value at idle, one may be failed
Use Tech 2 / GDS2 to run SCR performance tests after repair to clear countdown
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines P2A00 as a generic OBD-II code)
P2A00 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
Which Vehicles Commonly Get DURAMAX-P2A00?
- 2011-2016 Chevy Silverado 2500/3500 HD 6.6L Duramax LML
- 2011-2016 GMC Sierra 2500/3500 HD 6.6L Duramax LML
- 2017+ Chevy Silverado 2500/3500 HD 6.6L Duramax L5P
- 2017+ GMC Sierra 2500/3500 HD 6.6L Duramax L5P
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