Reductant Injection Air Pressure Sensor Circuit Low
The P2039 code means the vehicle's onboard diagnostic system has detected: Reductant Injection Air Pressure Sensor Circuit Low. This is a serious severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $200 - $600 (parts and labor)
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What Are the Symptoms of P2039?
- Check Engine Light on
- DEF system malfunction indicator
- Engine power reduction
- SCR system not functioning
- Possible speed limiter activation
What Causes P2039? (Most Likely First)
- Short to ground in air pressure sensor circuit Very High
- Failed air pressure sensor High
- Water intrusion in sensor connector Moderate
- Damaged wiring near exhaust heat Moderate
- PCM input circuit fault Low
Can I Still Drive with P2039?
Short distances only. P2039 is rated serious severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does P2039 mean?
P2039 indicates the reductant injection air pressure sensor circuit is reading below the minimum voltage, usually from a wiring short to ground or sensor failure.
Can I drive with a P2039 code?
Drive only short distances. The SCR system will not function, and some vehicles may activate a speed limiter if not repaired promptly.
How much does it cost to fix P2039?
Repair costs are typically $200 to $600 for sensor or wiring repair.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P2039?
-
Confirm P2039 with freeze frame data
-
Check air pressure sensor connector for moisture or corrosion
-
Measure sensor signal voltage at connector
-
Inspect wiring for shorts to ground
Sources 1
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)
Which Vehicles Commonly Get P2039?
- 2011-2019 Chevrolet Silverado 2500 6.6L Duramax
- 2009-2015 Volkswagen Jetta 2.0L TDI
- 2012-2018 BMW 328d 2.0L Diesel
- 2010-2016 Mercedes-Benz ML350 3.0L BlueTEC
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