P0122 code: Throttle/Pedal Position Sensor A Circuit Low
P0122 means throttle/Pedal Position Sensor A Circuit Low. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0122 means
The throttle position sensor (TPS) tells the computer how far the throttle is open so it can deliver the right fuel and, on drive-by-wire cars, control the throttle itself. P0122 means that sensor's signal is reading too low (or shorted to ground). Common causes are a failed sensor, a wire shorted to ground, or a corroded connector. On modern electronic throttle bodies the TPS is built in, so the fix may be the whole throttle body. Because the computer relies on this for throttle control, a fault can drop the car into a reduced-power "limp" mode.
P0122 symptoms
- Hesitation, surging, or poor throttle response
- Reduced-power or "limp" mode
- Stalling or rough idle
- Unexpected shifts on automatics
- Check-engine light, sometimes with a warning light
What it costs to fix P0122
Typical range: $50–$500 · about ~0.3–1.5 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Throttle position sensor (standalone) | $20–$100 | ~0.3–0.8 hrs |
| Electronic throttle body (integrated TPS) | $150–$500 | ~0.5–1.5 hrs |
| Wiring / connector repair | $10–$120 | ~0.5–1.5 hrs |
On older cars with a bolt-on TPS it's a cheap fix; on newer drive-by-wire cars the sensor is part of the throttle body, which is the expensive end. A wiring or connector repair is inexpensive once found.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0122 for my exact vehicle →
How to fix P0122
Moderate — doable at home with common tools and patience
- Inspect the TPS wiring for a ground short
A signal reading too low often means the signal wire is touching ground somewhere, so trace the harness from the throttle body looking for chafe points, melted spots near hot components, and rodent damage. Finding a grounded wire here is a repair measured in tape and solder, not parts.
- Check the connector
Unplug the TPS connector and examine both halves for corrosion, moisture, and loose terminals. A poor connection can drag the signal below the computer's plausibility limit just as effectively as a dead sensor.
- Sweep-test the sensor signal
Back-probe the signal wire (or watch TPS voltage on a scan tool) while opening the throttle slowly through its range. Healthy output climbs smoothly with no dropouts; a signal that sits near zero volts or falls off a cliff mid-sweep identifies the sensor as the fault.
- Verify the 5-volt reference
With the key on, confirm the sensor's reference wire carries about 5 volts. A missing reference means the problem is upstream — wiring or the computer's supply — and no number of new sensors will fix it.
- Replace the sensor and relearn
On older engines the TPS unbolts from the throttle body in minutes; on drive-by-wire engines the sensor is built in, so the throttle body is replaced as a unit and usually needs a relearn afterward. Match the replacement path to your engine's design.
DIY or shop? Wiring inspection, connector cleaning, and the voltage checks are all approachable DIY with a multimeter, and a bolt-on TPS swap on an older engine is about as easy as sensor jobs get. Drive-by-wire vehicles raise the bar: the part becomes a full throttle body and the relearn may demand a scan tool your garage doesn't have. Since this code can put the car in limp mode, plan the work so the vehicle isn't needed until it's done.
Tools for the DIY steps: Digital multimeter with back-probe pins · OBD2 scanner with live data · Screwdrivers and socket set · Electrical contact cleaner · Electrical tape and heat shrink for wiring repairs
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0122.
Start a case with P0122 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0122?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0122: common questions
Can I drive with P0122?
The code alone can't tell you that. It can cause hesitation or drop the car into reduced-power mode, which is risky in traffic. Get it inspected promptly, and if throttle response is unpredictable, have the car towed rather than driven.
Will P0122 cause limp mode?
It can. Because the computer depends on the throttle signal, a fault often triggers a reduced-power "limp" mode as a safety fallback — the car runs but acceleration is limited until it's fixed.
Is the TPS part of the throttle body?
On most modern drive-by-wire vehicles, yes — the throttle position sensor is integrated into the electronic throttle body, so the repair may mean the whole unit. Older cars often have a separate, cheaper bolt-on sensor.
How much does it cost to fix P0122?
Cheap on older cars with a standalone sensor; more on newer ones where it means a throttle body. Wiring/connector fixes are inexpensive. Diagnosis tells you which applies before you buy parts.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0122 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0122 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.