P0418: Secondary Air Injection System Relay A Circuit
6 vehicles · 2 makes · $100-$4,000 repair
P0418 is an OBD-II diagnostic trouble code meaning “Secondary Air Injection System Relay A Circuit.” The relay controlling the secondary air pump has a circuit fault. This code appears across 6 vehicle models from 2 manufacturers, with repair costs ranging from $100 to $4,000.
Common Causes
Typical Repair Cost
Based on 8 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0418, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Vehicles Affected (6)
FAQ
What does P0418 mean?
P0418 stands for "Secondary Air Injection System Relay A Circuit." The relay controlling the secondary air pump has a circuit fault.
What are the most common causes of P0418?
The most common causes of P0418 are: Failed relay, Wiring fault, Corroded connector, Fuse issue, ECU driver fault. The specific cause varies by vehicle.
How much does it cost to fix P0418?
Repair costs for P0418 range from $100 to $4,000, depending on the vehicle and root cause.
Which vehicles are affected by P0418?
Au7o has documented P0418 across 6 vehicle models from 2 manufacturers: Subaru, Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.