2012-2013 Impala Air Injection Pump: Why It Fails & How to Buy a Good Used One
This guide covers the common failures, symptoms, and crucial compatibility checks for the air injection pump on 2012-2013 Chevrolet Impalas with the 3.6L V6 engine.
- This pump ONLY fits 2012-2013 Impalas with the 3.6L V6 and California Emissions (RPO code NU6).
- Failure is almost always caused by water intrusion, either from a bad check valve or road splash.
- Always replace the air injection check valve at the same time as the pump to prevent repeat failure.
- A loud whining noise on cold start is the most common symptom of a failing pump.
Compatibility Warning: California Emissions (NU6) Only
Warning: This air injection pump only fits 2012-2013 Chevrolet Impala models equipped with the 3.6L V6 engine AND the California PZEV (Partial Zero-Emission Vehicle) emissions package. The option code for this package is NU6. Before ordering, you must verify your vehicle has this specific emissions package. You can find the RPO (Regular Production Option) codes on a silver sticker, typically located in the trunk on the spare tire cover or on the glove box door. If the code NU6 is not on this list, this part will not fit your vehicle.
Symptoms of a Failing Air Injection Pump
A bad air injection pump will almost always alert you with a Check Engine Light, but other symptoms can also point to a failure.
- Loud Whining or "Vacuum Cleaner" Noise on Cold Start: This is the most common symptom. A failing pump's bearings or motor will create a loud, unusual howling or whining noise for the first 30-90 seconds after starting the engine cold. The noise will stop once the pump's cycle is complete.
- Check Engine Light: The vehicle's computer monitors the air injection system. If it detects incorrect airflow or a non-functioning pump, it will trigger the Check Engine Light. Common trouble codes include P0411 (Incorrect Flow Detected), P2440 (Switching Valve Stuck Open), and P2444 (Pump Stuck On).
- Failed Emissions Test: Even if the car drives perfectly, a stored trouble code from a faulty air injection system will cause an automatic failure during an emissions inspection.
- Hesitation or Rough Idle on Cold Start: In some cases, a failing system can cause the engine to stumble or idle roughly for the first minute after a cold start before smoothing out.
Known Issues & Common Causes of Failure
The single most common cause of failure for these air pumps is moisture intrusion. Water can enter the pump in two primary ways:
- Internal Moisture (Exhaust Condensate): The system uses a one-way check valve to prevent hot exhaust gases from flowing back into the pump. When this valve fails or gets stuck open, it allows moisture-rich exhaust condensate to seep back into the air pump. This water corrodes the pump's internal electric motor and bearings, causing it to seize and fail.
- External Moisture (Road Splash): The pump is often located in an area susceptible to road spray. While designed to be water-resistant, damage to the housing or intake lines can allow water to be drawn into the unit, leading to failure.
Pro Tip: Always replace the secondary air injection check valve when replacing the pump. A faulty check valve is the most likely reason the original pump failed, and it will quickly destroy a replacement pump if not addressed.
Buying a Used Air Injection Pump: What to Check
A quality used OEM pump can be a reliable and cost-effective alternative to expensive new parts. Here’s what to inspect before you buy:
- Verify Compatibility: First and foremost, confirm the donor vehicle was a 2012-2013 Impala with the 3.6L V6 and the NU6 emissions package. Ask for the VIN to verify the vehicle's options or for a picture of the RPO sticker.
- Check for Water Damage: This is the most critical inspection. Look into the air inlet and outlet ports with a flashlight. Any signs of white, chalky residue, rust, or corrosion are red flags indicating water intrusion.
- Shake the Pump: Gently shake the unit. There should be no sloshing sounds (indicating trapped water) or rattling (indicating broken internal fan blades).
- Inspect the Electrical Connector: The pins in the electrical connector should be clean and free of corrosion or any signs of melting. Melted plastic suggests the old pump's motor was seized and overheating the circuit.
- Consider Mileage and Climate: A lower-mileage part is generally preferable, but a pump from a vehicle in a dry, rust-free climate may be in better condition than a low-mileage part from a wet or snowy region where road salt is used.
Replacement Overview
Replacing the air injection pump is a moderately easy job for a DIY mechanic with basic tools. The pump is typically located in the front passenger-side wheel well area or low on the front of the engine.
- Disconnect the negative battery terminal.
- Raise the front of the vehicle and secure it on jack stands.
- Remove the front passenger wheel and the plastic fender liner to access the pump.
- Disconnect the electrical connector and the large-diameter air hoses from the pump.
- Unbolt the pump and its mounting bracket from the vehicle frame.
- Installation is the reverse of removal. Remember to install the new or inspected check valve to protect your replacement pump.
| Part Type | Estimated Cost |
|---|---|
| New OEM (GM/ACDelco) | $250 - $350 |
| New Aftermarket (Dorman, etc.) | $150 - $220 |
| Used OEM | $75 - $150 |
| Shop Labor | $134 - $197 |
Related Part Numbers
Always verify part numbers with the VIN before purchasing. Known OEM part numbers for this pump include:
- 12634457
- 12630667
- 12634456
Frequently Asked Questions (FAQ)
Can I drive my Impala with a bad air injection pump?
Yes, you can drive the vehicle. A failed air pump does not affect the engine's primary performance or reliability once it has warmed up. However, the Check Engine Light will remain on, and the vehicle will not pass an emissions test.
Do I really need to replace the check valve at the same time?
Yes, it is highly recommended. The check valve is a common failure point that allows exhaust moisture to flow backward and destroy the pump. Installing a new pump without replacing a faulty check valve will likely lead to the new pump failing prematurely. The cost of a new check valve is minor compared to another pump replacement.
What is the NU6 / PZEV option?
NU6 is the GM Regular Production Option (RPO) code for vehicles built to meet Partial Zero-Emission Vehicle (PZEV) standards, which are stricter emissions regulations originally mandated by California and adopted by several other states. These vehicles often have additional or different emissions components, like this air injection system, compared to standard "Federal Emissions" vehicles.
Can I just delete or bypass the air injection system?
No, this is not recommended for a street-driven vehicle. Removing or disabling emissions components is illegal in many jurisdictions. Furthermore, the engine's computer will detect the missing system, resulting in a permanent Check Engine Light and a guaranteed failed emissions test.
Technical Specifications
OEM Part Numbers: 12634457 12630667 12634456
Fits 3.6L V6 LFX engine with NU6 (PZEV) California Emissions package only.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
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