Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that there's a problem with the car's system that helps reduce pollution. It's like when you have a fan that helps blow air into a fire to make it burn better, but the fan isn't working right.
The secondary air injection system helps reduce emissions by injecting air into the exhaust stream to help burn off excess fuel. When there's an issue with this system, it can trigger the P1423 code.
The P1423 code indicates a malfunction in the secondary air injection system on Bank 1 of the engine. This system is responsible for injecting fresh air into the exhaust system to aid in the catalytic converter's efficiency during cold starts. A fault in this system can be due to a variety of reasons, including a faulty air pump, blocked hoses, or a malfunctioning check valve.
• Check Engine Light is on
• Increased vehicle emissions
• Failed emissions test
• Possible rough idle during cold start
• Faulty air pump
• Blocked or leaking air hoses
• Malfunctioning check valve
• Electrical issues with the air pump relay
• Failed secondary air injection solenoid
Secondary Air Injection System: A system that injects air into the exhaust to reduce emissions.
Bank 1: The side of the engine with cylinder 1, usually the driver's side in a V-type engine.
• Use an OBD-II scanner to confirm the P1423 code.
• Inspect the secondary air injection system components for damage or blockages.
• Check the air pump and relay for proper operation.
• Test the check valve and solenoid for functionality.
• Replace the faulty air pump.
• Clear blockages in the air hoses.
• Replace the malfunctioning check valve.
• Repair or replace any damaged electrical connections.
• OBD-II scanner
• Multimeter
• Basic hand tools
• Vacuum pump
$150 - $500
Moderate
• BMW 3 Series
• Mercedes-Benz C-Class
• Audi A4
• Regularly inspect and maintain the air injection system.
• Ensure all hoses and connections are secure.
• Perform routine emissions system checks.
Emissions Control System
• Have the vehicle inspected by a professional if the Check Engine Light is on.
• Avoid driving in conditions that may worsen the issue, such as extreme cold starts.
• Schedule regular maintenance to prevent future occurrences.
Check with your vehicle manufacturer to see if emissions-related repairs are covered under warranty.
The P1423 code has been more common in vehicles with aging emissions systems, particularly in models from the late 1990s to early 2000s.
Moderate – Addressing this issue promptly can prevent further emissions system damage and ensure your vehicle passes emissions tests.
Driving with a malfunctioning emissions system may violate local emissions laws and contribute to environmental pollution.
• Engine at operating temperature
• Cold start conditions
The secondary air injection system components are typically located near the front of the engine bay, close to the exhaust manifold.
Q: Can I drive with a P1423 code?
A: While you can drive with this code, it's important to address it soon to avoid failing emissions tests and potentially causing more damage.
Q: How do I know if the air pump is faulty?
A: A faulty air pump may make unusual noises or fail to operate during a cold start. Testing with a multimeter can confirm electrical issues.
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Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
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Fitment Required · Vehicle-fitment part
Relevant when catalyst-efficiency or emissions faults persist after proper diagnosis.
Catalyst-efficiency faults sometimes point toward converter problems after proper testing.
Catalytic converters are highly vehicle-specific and should not be purchased by code alone.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.