Engine-Codes.com
Engine-Codes – GMC – P0418 GMC

P0418 GMC Code - Secondary Air Injection Pump Relay Control Circuit

Quick Answer

The P0418 diagnostic trouble code for GMC vehicles relates to the Secondary Air Injection Pump Relay Control Circuit. Common causes include Faulty Relay, The most common cause of the P0418 code is a faulty secondary air injection pump relay, Damaged Wiring. 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 GMC indicates Secondary Air Injection Pump Relay Control Circuit.
Common causes
Common causes include Faulty Relay, The most common cause of the P0418 code is a faulty secondary air injection pump relay, Damaged Wiring.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 12, 2024
💬 Need more help? Ask Auto Expert for instant answers — it's free!
AutoCodes App

Fix Your Car Smarter

Try the New AutoCodes App!

Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.

AutoCodes App on Google Play

Code P0418 GMC Description

The P0418 diagnostic trouble code for GMC vehicles relates to the Secondary Air Injection Pump Relay Control Circuit. This code indicates a problem with the control circuit of the secondary air injection pump relay, which is responsible for regulating the flow of air into the exhaust system to reduce emissions. The secondary air injection system helps reduce harmful emissions by injecting fresh air into the exhaust system during cold starts to assist in the combustion process.

OBDII Code P0418 GMC - Secondary Air Injection Pump Relay Control Circuit
P0418 GMC Code - Secondary Air Injection Pump Relay Control Circuit

Common Causes of P0418 GMC

  1. Faulty Relay - The most common cause of the P0418 code is a faulty secondary air injection pump relay.
  2. Damaged Wiring - Wiring harnesses connecting the relay to the control module or pump may be damaged or disconnected.
  3. Control Module Issues - Problems with the control module that regulates the relay can also trigger this code.
  4. Blown Fuse - A blown fuse in the secondary air injection system can cause the relay control circuit to malfunction.
  5. Water Intrusion - Water or moisture entering the secondary air injection system can lead to corrosion and electrical issues.

Symptoms of P0418 GMC

  1. Check Engine Light - The most common symptom of the P0418 code is the illumination of the check engine light on the vehicle's dashboard.
  2. Rough Idling - The engine may idle roughly or inconsistently due to issues with the secondary air injection pump.
  3. Decreased Fuel Efficiency - A malfunctioning secondary air injection pump can lead to decreased fuel efficiency as the engine may not be running optimally.
  4. Increased Emissions - The vehicle may produce higher emissions than usual, potentially leading to a failed emissions test.
  5. Engine Misfires - In severe cases, the engine may experience misfires or hesitation during acceleration.

How to Fix P0418 GMC

  1. Diagnose the Issue - Use a scan tool to read the code and pinpoint the exact cause of the problem.
  2. Inspect Wiring and Connections - Check the wiring harnesses and connections for any damage or corrosion and repair as necessary.
  3. Replace Relay - If the relay is faulty, replace it with a new one to restore proper function to the secondary air injection pump.
  4. Test System - After repairs are made, test the secondary air injection system to ensure it is functioning correctly.
  5. Clear Codes - Use a scan tool to clear the diagnostic trouble codes and reset the check engine light.

Cost to Fix P0418 GMC

The cost of repairing the P0418 code for GMC vehicles can vary depending on the specific cause of the issue and the labor rates in your area. On average, replacing a faulty relay or repairing wiring issues can range from $100 to $300. However, if the control module needs to be replaced or there are more extensive repairs needed, the cost could be higher. It's recommended to get a detailed estimate from a qualified mechanic to determine the exact cost for your specific situation. Remember that labor rates can vary, so it's advisable to shop around for the best deal.

When is the Code Detected?

If the fault detection circuit senses a voltage other than what the Powertrain Control Module (PCM) is expects, the fault line status changes causing the code P0418 to set.

Need more information about the P0418 GMC code?

Need more information on how to fix the P0418 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P0418 GMC code diagnosed by a professional: Find a repair shop in your area

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0418 GMC Code

1. What does the OBDII code P0418 mean on a GMC vehicle?

P0418 indicates a problem with the Secondary Air Injection Pump Relay Control Circuit, which helps reduce emissions by injecting fresh air into the exhaust system.

2. What are the common symptoms of P0418 on a GMC?

Symptoms may include an illuminated Check Engine Light, reduced engine performance, increased emissions, and possibly a failed emissions test.

3. What causes the P0418 code to appear?

Common causes include a faulty air pump relay, damaged wiring or connectors in the circuit, a blown fuse, or a defective secondary air injection pump.

4. How is P0418 diagnosed on a GMC vehicle?

A mechanic will use a scan tool to confirm the code, inspect the relay and wiring for damage, test the relay functionality, and check for power and ground in the circuit.

5. Can I drive my GMC with the P0418 code active?

While the vehicle may still be drivable, ignoring the issue can lead to increased emissions and potentially damage the catalytic converter over time.

6. How do you fix the P0418 code on a GMC?

Repairs may include replacing a faulty air injection pump relay, repairing damaged wiring, replacing the air pump if defective, or replacing a blown fuse.

7. Where is the secondary air injection pump relay located on a GMC?

The relay is typically found in the engine compartment fuse box, but its exact location may vary by model. Refer to your owner’s manual for specifics.

8. How much does it cost to fix the P0418 code on a GMC?

The repair cost can range from $50 to $300, depending on whether the issue is with the relay, wiring, or air pump.

9. Can a dirty or clogged air filter cause P0418 on a GMC?

No, a clogged air filter is not a direct cause of P0418, as the issue specifically involves the relay control circuit for the air injection system.

10. Will clearing the P0418 code with a scan tool fix the issue permanently?

No, clearing the code will only temporarily erase it. The underlying problem must be diagnosed and repaired to prevent the code from returning.

Discuss the causes and fixes for P0418 GMC OBDII Code

Submit a New Comment

Code P0418 GMC comments

No comments found for this page.