P1421 — Secondary Air Injection Valve Circuit Short To Ground

What Does P1421 Mean?

P1421 is a manufacturer-specific diagnostic trouble code: Secondary Air Injection Valve Circuit Short To Ground. This code applies to VOLKSWAGEN, BUICK, CADILLAC, CHEVY, CHRYSLER vehicles. Unlike generic OBD-II codes, manufacturer-specific codes are defined by the vehicle maker and may only apply to certain makes and models.

Symptoms of P1421

⚠️ Check Engine Light (MIL) illuminated
⚠️ Secondary Air Injection Valve not functioning as expected
⚠️ Related system may be in fail-safe mode
⚠️ Reduced engine performance

Common Causes

🔍 Faulty Secondary Air Injection Valve
🔍 Wiring or connector issue in Secondary Air Injection Valve circuit
🔍 Related mechanical or electrical fault
🔍 ECM/PCM issue (rare)

Frequently Asked Questions

What does P1421 mean?

P1421 indicates: Secondary Air Injection Valve Circuit Short To Ground. The vehicle's computer has detected that the Secondary Air Injection Valve is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1421?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1421 for extended periods may cause additional problems.

How much does it cost to fix P1421?

Repair costs for P1421 typically range from $80 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect Secondary Air Injection Valve and related wiring
🔧 Replace faulty Secondary Air Injection Valve

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

P1421: Secondary Air Injection Valve Circuit Short To Ground