Ford Check Engine Code
P0122 on Ford
Throttle Position Sensor / Switch A Circuit Low Input
Also covers: Lincoln, Mercury
P0122 on Ford: what makes it different
P0122 on Ford vehicles indicates the throttle position sensor (TPS) is reading below 0.2V when it should be at idle voltage (~0.5–0.9V). On modern Fords with electronic throttle, this typically forces "fail-safe mode" with limited throttle response and a wrench light.
Most-affected engines
- Most Ford engines from 2002 onward (electronic throttle body)
Common model years: 2002–present
Most likely cause on Ford
Failed throttle position sensor or dirty/sticky electronic throttle body
Known Ford engine-family issues
On the 5.4L 3V Triton (2004–2010 F-150, Expedition, Navigator), a dirty throttle body throwing P0122 is so common that many independent shops do a throttle-body cleaning before condemning the sensor. Carbon buildup on the throttle plate makes the TPS reading drift low at closed-throttle.
Ford-specific causes (most common first)
- Dirty throttle body — carbon buildup around the plate causes the TPS to read incorrectly. Common on 5.4L 3V Triton, 3.5L Ecoboost, and Duratec engines.
- Failed TPS (integrated into the throttle body on most Fords 2005+) — typically $150–$300 part
- Damaged TPS connector or wiring (corrosion at the plug, especially on F-150s exposed to road salt)
- PCM software needing TPS relearn after battery disconnect (forces fail-safe but doesn't throw P0122 alone)
Ford-specific diagnostic tip
Before replacing the throttle body assembly ($300+), pull the air intake duct, hold the throttle plate open with a screwdriver, and clean the back side of the plate and the bore with throttle-body cleaner. Many P0122 codes clear after this $5 fix. Disconnect the battery for 10 min after to force a TPS idle relearn.
Symptoms drivers report
- CEL
- Limp mode
- No throttle response
- Stalling
Typical repair cost on Ford
Most Ford owners fix P0122 for between $0 and $400, depending on which underlying cause turns out to be at fault. Start with the most-likely cause for your vehicle — Failed throttle position sensor or dirty/sticky electronic throttle body — before throwing parts at it.
Ford P0122 FAQ
Why is my F-150 stuck in fail-safe mode with P0122?
Ford's ETC (electronic throttle control) defaults to fail-safe — limited RPM, sluggish response, wrench light — when it can't trust the TPS reading. P0122 means the TPS is reading too low. Fix the TPS or clean the throttle body, clear the code, and the wrench light will go out after a successful drive cycle.
Can I just replace the TPS on a Ford or do I need the whole throttle body?
On 2005+ Fords, the TPS is integrated into the throttle body assembly and not separately serviceable from Ford. Aftermarket "TPS only" sensors exist for some applications but most owners just replace the whole electronic throttle body unit (Motorcraft DS-1126 etc., $200–$350).
Related codes
Drive a different make? See the general P0122 guide for cross-vehicle causes and symptoms.
Confirm P0122 on your Ford in 60 seconds
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