P1121 — Throttle Position Sensor Signal Not Consistent With Mass Air Flow Signal

What Does P1121 Mean?

P1121 is a manufacturer-specific diagnostic trouble code: Throttle Position Sensor Signal Not Consistent With Mass Air Flow Signal. This code applies to MAZDA, FORD, LINCOLN, MERCURY, OTHER 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 P1121

⚠️ Check Engine Light (MIL) illuminated
⚠️ Abnormal signal from Throttle Position Sensor
⚠️ Related system may operate erratically
⚠️ Reduced engine performance

Common Causes

🔍 Throttle Position Sensor producing abnormal signal
🔍 Electromagnetic interference affecting Throttle Position Sensor signal
🔍 Wiring issue distorting Throttle Position Sensor signal

Frequently Asked Questions

What does P1121 mean?

P1121 indicates: Throttle Position Sensor Signal Not Consistent With Mass Air Flow Signal. The vehicle's computer has detected that the Throttle Position Sensor is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1121?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1121 for extended periods may cause additional problems.

How much does it cost to fix P1121?

Repair costs for P1121 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.

Reported Repair Costs for P1121

Based on 3 owner-reported repair costs from NHTSA complaints.

Low End

$100

Typical

$400

High End

$1000

⚠️ These are owner-reported costs, not estimates. Actual costs vary by location, labor rates, and root cause. Source: NHTSA complaints database.

What To Do Next

Possible Fixes

🔧 Inspect Throttle Position Sensor and related wiring
🔧 Replace faulty Throttle Position Sensor

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.

P1121: Throttle Position Sensor Signal Not Consistent With Mass Air Flow Signal