P0418 GMC Code - Secondary Air Injection Pump Relay Control Circuit
Quick Answer
The Powertrain Control Module (PCM) controls the relay by grounding the control circuit via an internal switch called a driver. 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 GMC indicates Secondary Air Injection Pump Relay Control Circuit.
- 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 GMC Description
The relay controls the high current flow to the AIR injection pump integral bypass valve. This allows the PCM driver to only have to control the relatively low current used by the relay.
What are the Possible Causes of the DTC P0418 GMC?
- 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 GMC?
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 GMC 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.
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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.
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