P249D Chevrolet Code - Closed Loop Reductant Injection Control At Limit – Flow Too Low
Quick Answer
The selective catalytic reduction system reduces oxides of nitrogen (NOx) emissions by injecting a metered amount of diesel exhaust fluid or reductant into the exhaust gas stream entering the Diesel Particulate Filter (DPF). Common causes include Exhaust Leaks, Fuel contamination, Faulty Diesel Particulate Filter (DPF). Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P249D Chevrolet indicates Closed Loop Reductant Injection Control At Limit – Flow Too Low.
- Common causes
- Common causes include Exhaust Leaks, Fuel contamination, Faulty Diesel Particulate Filter (DPF).
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P249D Chevrolet Description
The ECM uses the 2 NOx sensors to control exhaust NOx levels. The NOx sensor measures the amount of NOx and oxygen in the exhaust system. The first NOx sensor is located at the outlet of the turbocharger and monitors the engine out NOx. The second NOx sensor is located in the DPF that monitors NOx levels exiting the DPF. The ECM varies the amount of reductant added by varying the reductant injector duty cycle in response to changes in engine exhaust out NOx levels.
What are the Possible Causes of the DTC P249D Chevrolet?
- Exhaust Leaks
- Fuel contamination
- Faulty Diesel Particulate Filter (DPF)
- Faulty NOx Sensor
- Diesel Exhaust Fluid
- Faulty Selective Catalyst Reduction (SCR) Catalyst
How to Fix the DTC P249D Chevrolet?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P249D Chevrolet code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P249D Chevrolet Code
1. What does the OBDII code P249D mean on a Chevrolet?
P249D indicates a problem with the closed-loop reductant injection system, where the flow of diesel exhaust fluid (DEF) is too low, causing the system to reach its control limit.
2. What are the common symptoms of P249D on a Chevrolet?
Common symptoms include the check engine light turning on, reduced fuel efficiency, decreased engine performance, and possible activation of limp mode.
3. What causes the P249D code to appear on a Chevrolet?
Potential causes include a clogged DEF injector, faulty reductant pump, low DEF levels, contaminated DEF fluid, or issues with the NOx sensor.
4. Can I keep driving my Chevrolet with the P249D code?
While the vehicle may remain drivable, ignoring the issue could lead to increased emissions, reduced performance, and potential damage to the emissions system.
5. How do I fix the P249D code on my Chevrolet?
Common fixes include cleaning or replacing the DEF injector, checking and refilling DEF fluid, replacing the reductant pump, or addressing faulty sensors like the NOx sensor.
6. How do I diagnose the P249D code on my Chevrolet?
Start by scanning the vehicle with an OBDII scanner to confirm the code, inspect the DEF system components for clogs or damage, and verify DEF fluid quality and levels.
7. What is the role of the reductant injection system in my Chevrolet?
The reductant injection system reduces NOx emissions by injecting DEF into the exhaust stream, where it reacts with exhaust gases to produce harmless nitrogen and water.
8. Can a bad NOx sensor cause the P249D code on a Chevrolet?
Yes, a malfunctioning NOx sensor can provide incorrect data to the ECU, leading to improper DEF injection and triggering the P249D code.
9. How much does it cost to repair the P249D code on a Chevrolet?
Repair costs vary depending on the issue but can range from $150 for cleaning or minor repairs to $1,000 or more for replacing major components like the reductant pump or NOx sensor.
10. How can I prevent the P249D code from recurring on my Chevrolet?
Regularly maintain the DEF system by using high-quality DEF fluid, keeping the tank filled, and cleaning or replacing components like the injector and sensors as needed.
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