OBD-II trouble code
P0220: Throttle/Pedal Position Sensor/Switch "B" Circuit Malfunction
The engine computer has detected a fault in the circuit for throttle position sensor B — the backup sensor in the redundant pair that tracks throttle or pedal position. Losing one of the pair breaks the cross-check the computer relies on for safe throttle control, so many vehicles respond with reduced-power mode.
Quick facts
- System
- Powertrain
- Category
- Throttle / Idle
- Severity
- High severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $100 – $700
- DIY difficulty
- Intermediate DIY
What does P0220 mean?
P0220 sets when the ECM sees an electrical problem in the throttle position sensor 'B' circuit — a voltage or resistance reading outside the window the manufacturer allows. Modern throttle systems, especially drive-by-wire designs, deliberately use two sensors reading the same position: sensor A and sensor B, usually built so their signals move in opposite directions or on different scales. The computer constantly compares them, and that redundancy is the safety net that lets an electronic throttle be trusted at all. P0220 means the B side of that pair has an open, short, or out-of-spec reading.
The practical consequences mirror the A-sensor code. With only one trustworthy signal, the ECM can no longer cross-check throttle position, so most vehicles fail conservative: reduced power, a capped throttle opening, a fixed fast idle, or full limp mode. Some cars show almost nothing beyond the check engine light; others become dramatically down on power. The causes also mirror the A side — a failed sensor element, damaged wiring, a corroded connector, or a problem with the shared 5-volt reference. Because both sensors often live in the same housing and share a connector, a fault that stores both P0120-family and P0220-family codes together points strongly at the shared harness, connector, or the assembly itself rather than two sensors dying at once.
On drive-by-wire vehicles, remember the pedal has its own redundant sensor pair, and manufacturers vary in which physical sensor they call 'B.' Service data for your specific vehicle tells you whether this code lives at the throttle body or the pedal. A correlation code such as P2135 or P2138 stored alongside is a strong clue the two signals disagree in a way the computer can measure — usually a genuine hardware fault rather than a passing glitch.
Common causes
- Failed throttle position sensor B (often part of the throttle body assembly)
- Open or shorted signal, ground, or 5-volt reference wiring on the B circuit
- Corroded, loose, or damaged sensor connector
- Accelerator pedal position sensor fault on drive-by-wire vehicles
- Carbon buildup or a sticking throttle plate causing erratic readings
- ECM fault (rare — verify the circuit first)
Symptoms
- Check engine light on with P0220 stored
- Reduced power / limp mode, sometimes with a wrench or throttle warning light
- Hesitation or sluggish throttle response
- Unstable or fixed high idle
- Hard starting or stalling in some cases
- Harsh or mistimed transmission shifts
- Sometimes no symptom beyond the warning light
Diagnostic steps
- 1.Scan for companion codes — P0120-family codes or a correlation code like P2135/P2138 reshapes the diagnosis toward shared causes.
- 2.Identify from service data whether sensor B lives on the throttle body or the accelerator pedal for your vehicle.
- 3.Inspect the connector and wiring at the throttle body (and pedal, if drive-by-wire) for damage, corrosion, and loose terminals.
- 4.Watch both sensor A and sensor B signals in live data through a slow throttle sweep — B should track A on its designed scale with no dropouts.
- 5.Verify the 5-volt reference and ground at the sensor connector.
- 6.If the sensor is integrated, inspect the throttle body for carbon and wear before replacing the assembly, and perform any required relearn after repair.
Repair cost
$100 – $700
Wiring and connector repairs land around $100-$250. Since sensor B is usually integrated into the throttle body or pedal assembly, replacement typically runs $300-$700 including labor, and many vehicles need a throttle relearn with a scan tool afterward. Confirm the fault electrically before buying an assembly — a corroded connector produces the same code for a fraction of the cost.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with throttle body cleaning preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.