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 the car's system that helps reduce pollution isn't working well. It's like trying to blow air through a straw that's blocked.
The secondary air injection system helps reduce emissions by injecting air into the exhaust stream. This code indicates that the system is not providing enough air flow.
The P140C code is triggered when the Engine Control Module (ECM) detects insufficient air flow in the secondary air injection system for both banks of the engine. This system is designed to pump fresh air into the exhaust to help reduce emissions, especially during cold starts.
• Check Engine Light illuminated
• Failed emissions test
• Rough idle during cold start
• Faulty air injection pump
• Blocked air injection passages
• Defective air injection check valve
ECM: Engine Control Module
Emissions: Pollutants released into the air from the vehicle's exhaust
• Check for any other related codes.
• Inspect the air injection pump and hoses for damage or blockages.
• Test the air injection check valves for proper operation.
• Replace the air injection pump if faulty.
• Clear any blockages in the air injection passages.
• Replace defective air injection check valves.
• OBD-II scanner
• Multimeter
• Vacuum pump
$200 - $700
Moderate
• BMW 3 Series
• Mercedes-Benz C-Class
• Audi A4
• Regular maintenance of the air injection system.
• Ensure no blockages in the air passages.
• Use quality fuel to reduce carbon buildup.
Emissions Control System
• Do not ignore the Check Engine Light.
• Have your vehicle inspected by a professional if you notice symptoms.
• Consider regular emissions system checks.
Check with your vehicle manufacturer for emissions-related warranty coverage.
This code has been more common in vehicles with aging secondary air injection systems, especially in colder climates.
Moderate – It may not affect immediate drivability but should be addressed to pass emissions tests and avoid further damage.
Driving with a malfunctioning emissions system may be illegal in some areas due to pollution regulations.
• Engine at operating temperature.
• Cold start conditions.
The secondary air injection pump is typically located near the front of the engine bay, connected to the exhaust manifold.
Q: Can I drive with a P140C code?
A: Yes, but it's not recommended to ignore it as it affects emissions and could lead to further issues.
Q: Will this code affect my car's performance?
A: It may cause rough idling during cold starts, but generally won't affect overall performance.
High-End · Full-system diagnostics
A full-system bidirectional platform aimed at advanced DIY users and professional diagnostic workflows.
Network faults often require full-system access instead of a generic code reader alone.
View on Amazon
Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
View on Amazon
Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
View on AmazonThese are optional diagnostic tools, not guaranteed fixes. As an Amazon Associate I earn from qualifying purchases.
Fitment Required · Vehicle-fitment part
Relevant for airflow, fuel-trim, and intake-metering faults after confirming the sensor is actually at fault.
Airflow and fuel-trim codes can involve the mass air flow sensor after proper diagnosis.
Verify the sensor design and fitment for your exact vehicle.
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.