P0122

What P0122 means

Your throttle body (or gas pedal, on newer drive-by-wire cars) has a sensor that tells the computer how far the throttle is open, or how far you've pressed the pedal. P0122 means that signal came in lower than it should, or dropped to nearly zero, at some point. The computer can't tell if you actually meant to let off the gas or if the sensor is just giving it bad information. It flags the code either way.

Is it safe to drive

This depends on how the car is acting right now. If the engine is idling rough, hesitating when you press the gas, surging, or the throttle response feels off in any way, don't keep driving it. Modern cars often go into a limp mode when this sensor fails, which limits engine power and rpm on purpose, as a safety measure. That's the computer protecting itself, not a sign to ignore. If the car is running fine and the code just popped up on a scanner with no symptoms, it's a lower-priority visit, but still worth getting looked at soon rather than waiting for it to get worse.

What usually causes it

Commonest first:

• Wiring problem: a chafed wire, corroded connector, or loose plug at the throttle body or pedal sensor. This is the most common cause and it's cheap to fix once found.
• The throttle position sensor itself failing or drifting out of range.
• On drive-by-wire cars, the accelerator pedal sensor assembly instead of anything at the throttle body.
• A bad ground connection affecting the sensor circuit.
• Less often, a problem with the engine computer itself, though this is rare and shouldn't be assumed early.

Which of these is most likely depends on the car. Some engines use a simple throttle position sensor on a cable-operated throttle body. Others use an electronic throttle body with two sensors built in, and a separate pedal sensor with two more. More sensors means more wiring to check before anything gets replaced.

Diagnosis and rough cost

The right way to diagnose this is to check the wiring and connectors first, then test the sensor's actual output against what the computer expects, rather than replacing the throttle body or pedal assembly right away. A shop doing this properly will pull up live sensor data on a scan tool and watch it move as the throttle is worked by hand.

If it turns out to be a wiring or connector issue, the repair can be inexpensive, sometimes under $150 in labor with no parts needed. If the throttle body or pedal sensor needs replacing, parts alone can run anywhere from around $150 to $500 or more depending on the make, plus labor. We wouldn't quote a number without seeing the car and the code data first, since it really does vary that much car to car.

We're at 28801 Meridian E in Graham, open Monday through Friday, 8 to 5. Bring it in and we'll pull the live data before we tell you what needs replacing.

Generic OBD-II guidance — manufacturer-specific codes and causes vary by make, so always confirm against your vehicle. A code identifies a system or condition; it does not, on its own, prove which part has failed.