P0220
Throttle/Pedal Position Sensor/Switch B Circuit MalfunctionP0220 is a generic OBD-II powertrain diagnostic trouble code: Throttle/Pedal Position Sensor/Switch B Circuit Malfunction. It is logged by the engine control unit when the throttle monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0220 means
P0220 is set when the PCM detects a voltage or signal condition in the throttle position sensor (TPS) or accelerator pedal position (APP) sensor "B" circuit that falls outside the manufacturer's expected operating range, without the fault being specific enough to qualify as a definitively low (P0222) or definitively high (P0223) reading. Modern drive-by-wire (electronic throttle control) systems employ two independent TPS channels — labelled "A" and "B" — inside the same sensor housing. The PCM continuously compares both channels: channel A typically climbs from ~0.5 V to ~4.5 V as the throttle opens, while channel B runs an inverse or offset mirror curve. Any divergence or out-of-spec reading on the B channel triggers P0220.
Because redundancy is fundamental to electronic throttle safety, loss of a valid B-channel signal — even when channel A appears healthy — is treated as a system integrity failure. The PCM will typically command a reduced-power (limp) strategy, capping engine output and vehicle speed to protect the drivetrain. In severe cases the engine may be forced to idle only or stall, as the PCM cannot confirm driver intent without agreement from both sensor channels.
P0220 commonly accompanies sibling codes P0120 (TPS A circuit), P2135 (TPS A/B correlation fault), and P0121/P0221 (range/performance). The repair sequence should resolve all related codes before confirming a fix, as a correlation fault may mask whether A or B is the root cause.
Common causes
Most-frequently reported root causes when P0220 is logged.
-
1
Faulty throttle position sensor (TPS) — worn, heat-damaged, or contaminated B-channel resistive track inside the sensor assembly.
-
2
Faulty accelerator pedal position (APP) sensor — internal failure of the B-channel element within the pedal assembly.
-
3
Damaged, corroded, or chafed wiring in the TPS/APP B-circuit harness between the sensor and the ECM.
-
4
Loose, bent-pin, or oxidised connector at the throttle body or pedal sensor reducing signal integrity.
-
5
Contaminated or sticking throttle body causing the throttle plate position to disagree with the PCM's expected position, producing out-of-range voltage.
-
6
Misaligned TPS mounting — sensor physically out of position causing the voltage output to be outside the calibrated window.
-
7
Defective PCM unable to correctly interpret B-channel voltage (rare, typically a last-resort diagnosis after wiring and sensors are confirmed good).
Symptoms drivers notice
How to diagnose P0220
A typical diagnostic flow when this code is present.
-
1
Scan for all stored codes and record freeze-frame data; look for companion codes P0120, P0121, P0222, P0223, or P2135 that narrow the failure to wiring vs. sensor vs. correlation.
-
2
Perform a thorough visual inspection of the throttle body and accelerator pedal connector — check for bent pins, corrosion, water ingress, and chafed wire insulation.
-
3
With the key on and engine off, monitor live TPS A and B voltage channels simultaneously on a scan tool while slowly sweeping the throttle; the B-channel should trace its expected curve smoothly without dropouts or flat spots.
-
4
Use a digital multimeter to verify the 5 V reference supply and clean chassis ground at the TPS/APP connector; a missing reference or floating ground will produce out-of-spec B-channel readings without the sensor itself being faulty.
-
5
Perform a wiggle test on the wiring harness while monitoring live B-channel voltage to reveal intermittent open circuits or poor connector contact.
-
6
Clean the throttle body if carbon deposits are present, as stiction on the throttle plate can cause the B-channel to read outside its expected position window.
-
7
Replace the TPS or APP sensor if wiring and reference voltage are confirmed good and the B-channel voltage remains abnormal or absent.
Related powertrain codes
- P0120 — Throttle Position Sensor/Switch A Circuit Malfunction
- P0121 — Throttle Position Sensor/Switch A Circuit Range/Performance Problem
- P0122 — Throttle Position Sensor/Switch A Circuit Low Input
- P0123 — Throttle Position Sensor/Switch A Circuit High Input
- P0124 — Throttle Position Sensor/Switch A Circuit Intermittent
- P0221 — Throttle/Pedal Position Sensor/Switch B Circuit Range/Performance
Frequently asked questions
Why does the car go into limp mode for a sensor B fault when sensor A seems fine?
Drive-by-wire throttle systems are designed with dual redundancy specifically because a stuck or uncommanded wide-open throttle is a life-safety hazard. The PCM is programmed to distrust a single healthy channel when the second channel disagrees or reads out of range — it cannot determine which sensor is lying. Limp mode is the legally mandated failsafe response to any unresolvable throttle signal ambiguity.
What is the difference between P0220 and P0120?
P0120 relates to the "A" channel of the throttle/pedal position sensor, while P0220 relates to the "B" channel. On a drive-by-wire throttle body the A channel is the primary signal and the B channel is the inverse redundant signal. Both are monitored independently, so a fault on either produces its own dedicated code.
Can cleaning the throttle body fix P0220?
Sometimes. Heavy carbon deposits can cause the throttle plate to stick slightly, producing a B-channel voltage that is technically out of the calibrated range for the actual commanded position. Cleaning removes this mechanical offset. However, if the sensor's internal resistive track is worn, cleaning will not help — the sensor itself must be replaced.
Is P0220 safe to drive on temporarily?
If limp mode is active, the vehicle is drivable at low speed for a short distance to reach a workshop, but prolonged driving in limp mode risks stalling in traffic and provides no protection if the sensor A channel also fails. If the throttle response is erratic or unpredictable, the vehicle should be towed rather than driven.
Disabling P0220 in software
RaceTune can permanently disable P0220 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0220 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
Upload your file