P1418 Secondary Air Injection Monitor Low Voltage
The P1418 code indicates that the powertrain control module (PCM) has detected a voltage signal below the expected threshold in the secondary air injection (SAI) system monitor circuit. The SAI system pumps fresh air into the exhaust manifold during cold starts to accelerate oxidation of hydrocarbons (HC) and carbon monoxide (CO), reducing emissions. The monitor circuit checks system operation, and a low voltage signal can point to an open circuit, short to ground, or a faulty monitoring component. On Ford vehicles, this code specifically relates to the SAI feedback circuit.
01. Most Common Causes
- SAI monitor circuit wiring shorted to ground
- Open circuit in SAI monitor sensor wiring
- Faulty secondary air injection (AIR) control valve
- Failed or restricted secondary air pump
- Corroded or loose electrical connections in the SAI circuit
- PCM with outdated software or internal failure (rare)
02. Symptoms You Will Notice
- Illuminated check engine light
- Possible increased emissions during cold start
03. Step-by-Step Diagnosis
Scan for P1418 and any related codes
Visually inspect SAI system wiring and connectors for damage, corrosion, or looseness
Test the SAI monitor circuit for shorts to ground or opens using a multimeter
Check the secondary air pump and AIR control valve for proper operation
Verify PCM software is up to date; if all else fails, consider PCM replacement
1. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive with this code, but the vehicle may fail an emissions test. The issue should be diagnosed and repaired soon to avoid potential catalytic converter damage from unburned fuel.
How much does it cost to fix?▼
Repair costs typically range from $100 to $600, depending on the root cause. A simple wiring repair may cost under $200, while replacing the secondary air pump or control valve can run $300–$600.