P0223
- Powertrain
- Generic (SAE)
- Emissions
Get it looked at now
An out-of-range throttle signal means the failsafe is effectively guaranteed, and it can engage the instant the fault reappears. Sudden loss of throttle authority in traffic is a genuine hazard even though nothing mechanical is being destroyed.
- Safe to drive
- Drive only if you must, short and slow. Reduced power can engage instantly. Repair before any highway use.
Throttle/Pedal Position Sensor/Switch "B" Circuit High Input
The "B" signal wire from your throttle or pedal position sensor is sitting at a voltage higher than the computer will accept — higher than any real throttle position could produce. That is an electrical fault in the circuit, not a worn-out part by default.
The module applies a fixed upper voltage ceiling to the B channel, independent of what the throttle or pedal is actually doing. Exceeding it means the signal line is being pulled toward supply. Three things do that: the signal line shorted to the 5V reference or to battery voltage, an open or high-resistance sensor ground that lets the signal float upward, or a sensor element that has failed shorted internally. Because the module can no longer trust a throttle input, essentially every drive-by-wire vehicle enters a reduced-power failsafe.
How the car detected itRaw analog-to-digital voltage on the B channel compared against a fixed ceiling for a short debounce period, regardless of engine operating point. There is no plausibility calculation involved — that is exactly what separates a circuit-high code from a range/performance code like P0221. Many vehicles can set this with the key on and the engine not running. The threshold voltage and debounce time are vehicle-specific.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Drive only if you must, short and slow. Reduced power can engage instantly. Repair before any highway use.
- Urgency
- Get it looked at now
- Will it pass emissions
- No
- If ignored
- Intermittent shorts become permanent ones. Expect the vehicle to end up idling only and refusing throttle. A chafed harness causing this will keep wearing and can take other circuits with it, turning a simple repair into a harness section replacement.
- Check engine light
- Solid
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
Many vehicles show no symptom at all beyond the warning light. The absence of a symptom does not mean the fault is not real.
These are the causes this code can have. For the order to work through them in, see what to check first.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | TPS B circuit shorted to supply voltage | Very common | — |
| 2 | TPS B element failed | Common | — |
| 3 | Connector pins corroded - high contact resistance | Occasional | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
In order. Each of these is cheaper or faster than what follows it, and each one can make the rest unnecessary.
Whether the code is current or historic
A code present right now can be measured and proven. A historic code needs a wiggle test and a datalog instead, and the diagnostic path is completely different.
The connector for water, coolant, or oil intrusion
Moisture bridging the 5V reference into the signal pin is one of the most common real causes and mimics a dead sensor perfectly. Wash it, dry it, and retest before condemning anything.
Harness routing near hot or moving parts
A signal wire rubbed through against a bracket or the throttle body can short to a nearby supply wire. Follow the run with your fingers, not just your eyes.
Other codes on the same 5V reference circuit
A cluster of codes across several sensors points at a shared reference or ground problem rather than at the throttle sensor itself.
Any recent work on the intake, pedal assembly, or harness
A pinched wire during reassembly, or an added throttle controller or tuner spliced into the signal, is a far more likely cause than a sensor that failed on its own.
Read the B channel with the key on and the engine off, through the full pedal sweep
Tools Scan tool with live data
Confirm the fault is live and see how it behaves. Compare against the A channel at the same moment.
ExpectedOn a live fault, B reads pegged at or near its maximum regardless of pedal position, while A responds normally. If B behaves and the code is historic, move to wiggle testing.
Unplug the sensor, then jumper the signal pin to sensor ground at the harness connector
Tools Scan tool, fused jumper wire, basic hand tools
Unplug the sensor and note the reported value. Then bridge the signal pin to the sensor ground pin at the harness side with a fused jumper wire and watch the scan tool. The jumper is what makes this test conclusive, because it gives the same answer no matter which way the module biases the input.
ExpectedMany modules bias this input high, so a high reading with the sensor merely unplugged is normal and proves nothing on its own. With signal jumpered to sensor ground, the reported value should drop to minimum. If it does not, the signal wire is shorted to voltage, is open, or the module input has failed — and that is what points at wiring or the module. If it does drop to minimum, the signal wire and module input are capable of reading low, and the sensor or its ground is the remaining suspect.
Voltage-drop the sensor ground with the circuit connected and loaded
Tools Digital multimeter with backprobes
Backprobe the sensor ground pin and measure to battery negative while the circuit is live. Do not test this with the connector unplugged — a resistive ground can look perfect unloaded.
ExpectedOnly a small drop, a few tenths of a volt at most. An open or resistive ground allows the signal to float toward reference and is a frequently missed cause of a circuit-high code.
Measure the 5V reference at the sensor connector
Tools Digital multimeter
Check it both static and while the harness is flexed. Note whether other sensors share this reference.
ExpectedSteady and close to nominal — a 5V reference should sit near 5.0V. The exact nominal value and which sensors share it are vehicle-specific.
Isolate a short to voltage on the signal wire
Tools Digital multimeter, wiring diagram for the specific vehicle
Disconnect the harness at both the sensor and the module. Check the signal wire for continuity or voltage to battery positive and to the reference wire, and for continuity end to end.
ExpectedNo continuity or voltage between the signal wire and any supply. Near-zero resistance from the sensor connector to the corresponding module pin. Pin locations vary by vehicle — use the correct diagram, never assume.
Wiggle, heat, and cool the harness while monitoring, if the fault is intermittent
Tools Scan tool with graphing, heat gun, freeze spray
Work section by section with the scan tool graphing the B channel. Cover the pedal end, the bulkhead pass-through, and the engine bay run.
ExpectedA stable trace. Any spike that follows your hands or a temperature change pins the fault to that section.
Substitute a known-good sensor only after the wiring is proven
Tools Known-good or new sensor, scan tool for relearn
If reference, ground, and signal wiring all test correct and the signal is still pegged high with the sensor connected, the sensor element is the remaining suspect.
ExpectedSignal returns to a normal range and tracks the A channel. Perform the manufacturer's throttle or pedal relearn afterward if the vehicle calls for one.
| Repair | Only after you confirm | Typical cost | Who |
|---|---|---|---|
| Repair the shorted or chafed section of signal wiring | Continuity or voltage measured between the signal wire and a supply with both ends disconnected, or a fault that appears when a specific section is flexed | $100–$400 | DIY |
| Clean, dry, or replace the sensor connector and its terminals | Moisture, corrosion, or spread terminals found in the connector, with the fault clearing after the repair and not returning on retest | $100–$350 | DIY |
| Repair the open or high-resistance sensor ground circuit | Excessive voltage drop on the ground leg with the circuit loaded, and the signal returning to normal range once the ground is restored | $100–$400 | DIY |
| Replace the throttle position sensor or electronic throttle body | Signal still pegged high with a verified good reference, ground, and signal wire — the reported value dropping to minimum when signal is jumpered to sensor ground, and normal after substituting a known-good sensor | $250–$900 | DIY |
| Replace the accelerator pedal position sensor assembly | The high signal traced to the pedal sensor specifically, with its wiring, reference, and ground all proven good | $150–$450 | DIY |
| Remove an aftermarket throttle controller, pedal box, or tuning device from the signal circuit | The fault disappearing when the device is removed and the harness returned to stock | $0–$150 | DIY |
| Reprogram or replace the engine control module | The reported value staying pegged high with the signal pin jumpered to sensor ground at the module connector, with the signal wire proven continuous and free of shorts to supply | $600–$2,000 | Shop |
US independent shop rates, parts plus labor. Wiring repairs vary widely with how buried the damaged section is — a chafe in the open engine bay is cheap, one inside a loom behind the intake manifold is not. Factory-level scan capability is often needed for the relearn.
- Replacing the sensor first. A bad ground and a bad sensor produce identical readings on a scan tool.
- Reading a high value with the sensor simply unplugged as proof of a wiring or module fault. Most of these inputs are biased high, so that reading is normal — only the jumper-to-ground test separates the two.
- Skipping the connector inspection. Water in a pedal or throttle connector bridges reference to signal and is invisible unless you actually open and look.
- Testing grounds and references with the connector unplugged. Resistive faults hide until the circuit is under load.
- Treating P0223 and P0221 as the same problem. High input is a hard electrical range fault. Range/performance is a plausibility fault. They need different tests.
- Repairing the wiring but skipping a required relearn, then blaming the repair when idle or throttle response is wrong.
- Not verifying the fix with a road test. On several manufacturers the failsafe latches until a specific set of conditions is met after clearing.
- Throttle Position Sensor B
- Tps Wiring
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Reviewed
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