P0418 Code - Secondary Air Injection System Relay 'A' Circuit Malfunction
Quick Answer
An air pump is used on the vehicle to lower tail pipe emissions on start-up. Common causes include Faulty Air Pump inoperative, Air bypass solenoid harness is open or shorted, Air bypass solenoid circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
- What it means
- P0418 indicates Secondary Air Injection System Relay 'A' Circuit Malfunction.
- Common causes
- Common causes include Faulty Air Pump inoperative, Air bypass solenoid harness is open or shorted, Air bypass solenoid circuit poor electrical connection.
- Severity
- Moderate - service should be scheduled soon.
- Can I drive?
- The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.
Code P0418 Description
What are the Possible Causes of the DTC P0418?
- Faulty Air Pump inoperative
- Air bypass solenoid harness is open or shorted
- Air bypass solenoid circuit poor electrical connection
How to Fix the DTC P0418?
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 P0418 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.
Need more information about the P0418 code?
Need more information on how to fix the P0418 code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P0418 code diagnosed by a professional: Find a repair shop in your area
Information for Specific Makes
- P0418 Audi — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Buick — Secondary Air Injection Pump Relay Control Circuit
- P0418 Cadillac — Secondary Air Injection Pump Relay Control Circuit
- P0418 Chevrolet — Secondary Air Injection Pump Relay Control Circuit
- P0418 Chrysler — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Dodge — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 GMC — Secondary Air Injection Pump Relay Control Circuit
- P0418 Isuzu — Secondary Air Injection Pump Control Circuit
- P0418 Jeep — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Lexus — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Mercedes-Benz — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Pontiac — Secondary Air Injection Pump Relay Control Circuit
- P0418 Saturn — Secondary Air Injection Pump Relay Control Circuit
- P0418 Subaru — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Toyota — Secondary Air Injection System Relay 'A' Circuit Malfunction
- P0418 Volkswagen — Secondary Air Injection System Relay 'A' Circuit Malfunction
Frequently Asked Questions about P0418 Code
1. What are the common symptoms of OBDII code P0418?
- Common symptoms of P0418 include illuminated Check Engine Light (CEL), rough idling, decreased engine performance, and increased emissions.
2. What does the OBDII code P0418 indicate about the Secondary Air Injection System Relay 'A' Circuit?
- P0418 indicates a malfunction in the relay 'A' circuit of the Secondary Air Injection System, which is responsible for reducing vehicle emissions during cold engine starts.
3. What are the potential causes of the Secondary Air Injection System Relay 'A' Circuit Malfunction (P0418)?
- Potential causes of P0418 include a faulty relay, damaged wiring or connectors in the circuit, a blown fuse, or a malfunctioning Secondary Air Injection pump.
4. How serious is the OBDII code P0418?
- While P0418 may not cause immediate harm to the vehicle, it can lead to increased emissions and potential damage to the catalytic converter over time if left unresolved.
5. Can I continue driving with OBDII code P0418 unaddressed?
- It is generally not recommended to drive with an unresolved P0418 code, as it can negatively impact engine performance and emissions, and may lead to additional issues down the line.
6. How can I diagnose the cause of OBDII code P0418 at home?
- You can start diagnosing P0418 by checking the relay, inspecting the wiring and connectors for damage, testing the fuse, and ensuring the Secondary Air Injection pump is functioning properly.
7. Is it possible to clear the OBDII code P0418 and see if it returns?
- Clearing the code may temporarily turn off the Check Engine Light, but if the underlying issue causing P0418 is not fixed, the code is likely to reappear after some driving cycles.
8. How much does it typically cost to repair OBDII code P0418?
- The cost of repairing P0418 can vary depending on the root cause, but it may range from a simple fuse replacement to a more involved relay or pump replacement, costing anywhere from $100 to $500 or more.
9. Will fixing the Secondary Air Injection System Relay 'A' Circuit Malfunction (P0418) improve fuel efficiency?
- Addressing P0418 can potentially result in improved fuel efficiency, as a properly functioning Secondary Air Injection System helps optimize engine performance and emissions control.
10. Can a DIY enthusiast with basic mechanical skills repair OBDII code P0418?
- Depending on the specific cause, a DIY enthusiast with basic mechanical skills may be able to address P0418 by replacing a fuse or relay, but more complex issues may require professional diagnosis and repair.
Discuss the causes and fixes for P0418 OBDII Code
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
