OBD-II trouble code
P0415: Secondary Air Injection System Switching Valve B Circuit Malfunction
An electrical fault in the control circuit for the secondary air injection system's "B" switching valve — usually wiring, the valve solenoid, or a relay.
Quick facts
- System
- Powertrain
- Category
- Emissions / Secondary Air
- Severity
- Low severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $80 – $500
- DIY difficulty
- Advanced DIY
What does P0415 mean?
The secondary air injection (AIR) system pumps fresh air into the exhaust for the first minute or so after a cold start, helping burn off unburned fuel and getting the catalytic converter up to temperature quickly. Switching (or combination) valves control when that air is allowed into the exhaust stream and block hot exhaust from flowing backward into the pump. P0415 flags an electrical problem in the control circuit of switching valve "B" — on V-configuration engines typically the valve serving the second bank, mirroring valve "A" codes P0413/P0414.
This is a circuit code: the computer sees an open, short, or implausible load when it commands the valve — the plumbing may be fine. Common culprits are a failed valve solenoid, corroded connectors (the system lives in a damp, hot area and frequently ingests moisture), damaged wiring, or a bad relay/fuse feeding the circuit.
Beyond a check engine light and a failed emissions test, symptoms are usually minor — the system only operates briefly after cold starts.
Common causes
- Failed switching valve solenoid ("B" side)
- Corroded or moisture-damaged connector
- Open or shorted wiring in the valve control circuit
- Blown fuse or failed relay for the AIR system
- Melted or heat-damaged harness near the exhaust
- PCM driver fault (rare)
Symptoms
- Check engine light on
- Failed emissions inspection
- Possible brief rough running right after cold start
- Occasionally a vacuum-like hiss or pump running longer than normal
- Often no drivability symptom at all
Diagnostic steps
- 1.Scan for companion AIR codes (P0410-P0414, P0416-P0418) to see how much of the system is implicated.
- 2.Inspect the valve B connector and wiring for corrosion, heat damage, and moisture.
- 3.Check the fuse and relay feeding the AIR system.
- 4.Command the valve with a scan tool and listen/feel for actuation; measure solenoid resistance against spec.
- 5.Verify power and ground at the valve connector during the command.
- 6.Replace the valve or repair wiring as found; clear codes and confirm the cold-start cycle completes without resetting.
Repair cost
$80 – $500
Switching/combination valves typically run $50-$200 with modest labor when accessible. Wiring and relay fixes are cheaper. If moisture has been cycling through the system, inspect the pump too — they often fail together.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with secondary air injection pump replacement preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.