P0228 is a throttle/pedal position sensor code that points to a high voltage signal on “Sensor C.” In plain language, your engine computer is seeing a throttle or accelerator pedal signal that’s higher than it should ever be, so it flags a fault and often throws the car into limp mode. You’ll usually notice poor throttle response, reduced power, and a glowing check engine light or traction light. The good news is this code is very fixable with proper diagnosis, and you can often avoid major repairs by catching it early.
What Does P0228 Mean?
P0228 stands for “Throttle/Pedal Position Sensor C Circuit High Input.” Your ECU constantly monitors the throttle body and accelerator pedal through several position sensors (A, B, C, etc.). Sensor “C” is one of those redundant signals used to verify that the throttle angle and pedal position match what you’re asking for with your right foot.
When the ECU sees the Sensor C signal voltage stuck too high or reading far above the expected range for a certain pedal position, it sets P0228. This is a safety-related code because incorrect throttle readings can affect engine power, idle, and traction control.
Quick Reference
- Code: P0228
- Definition: Throttle/Pedal Position Sensor C Circuit High Input
- Common Symptoms: Limp mode, poor acceleration, high or unstable idle
- Likely Causes: Faulty throttle position sensor, pedal sensor, wiring issues, or bad throttle body
- Risk Level: Moderate to high – drivability and safety concern
Real-World Example / Field Notes
In the shop, I see P0228 most often on drive-by-wire vehicles that already have some miles on them. A typical case: customer comes in saying, “The car suddenly lost power on the highway and won’t rev past 2,500 rpm.” Scan tool shows P0228 plus maybe another throttle code. On inspection, I often find corrosion in the throttle body connector or a worn throttle body assembly with internal sensor failure. Cleaning the connector and checking the wiring sometimes saves the day, but many times the fix is a new throttle body followed by a throttle relearn procedure.
Symptoms of P0228
- Check engine light on – Often accompanied by traction control or stability control warning lights.
- Limp mode / reduced power – ECU limits throttle opening to protect the engine and maintain control.
- Poor acceleration – Slow response when you press the gas pedal, or no response beyond a certain point.
- Unstable or high idle – Idle may surge, hang high, or feel inconsistent.
- Throttle hesitation – Delay or stumble when taking off from a stop or during passing maneuvers.
- Stalling at idle – In more severe cases, the engine may stall when coming to a stop.
- Transmission shifting issues – On some automatics, odd shift timing due to incorrect load/throttle data.
Common Causes of P0228
Most Common Causes
- Faulty throttle position sensor (TPS) in the throttle body – Internal wear or failure in the Sensor C track causes a high voltage signal.
- Defective accelerator pedal position sensor (APP) – On some designs, Sensor C is part of the pedal assembly instead of the throttle body.
- Corroded or loose throttle body connector – Moisture, oil, or dirt in the connector can skew voltage readings.
- Damaged wiring harness – Chafed, pinched, or shorted wires in the throttle/APP circuit can force the signal high.
- Previous incorrect repairs or modifications – Spliced wires, aftermarket remote starters, or pedal controllers sometimes introduce signal issues.
Less Common Causes
- Faulty ECU/PCM – Internal failure in the engine computer’s input circuit is rare but possible.
- Poor engine or chassis grounds – High resistance grounds can distort reference and signal voltages.
- Water intrusion in harness – Vehicles in harsh climates or flood damage cases may have hidden corrosion.
- Throttle body carbon buildup – Heavy deposits can cause abnormal throttle movement, sometimes triggering related codes along with P0228.
- Incorrect throttle body or pedal replacement – Installing the wrong part number or skipping the relearn procedure can lead to sensor mismatch codes.
Diagnosis: Step-by-Step Guide
You’ll want a basic tool set plus a decent scan tool (preferably one that shows live data), a digital multimeter, and access to wiring diagrams or service information. If you’re comfortable with electrical checks, you can do most of this at home; otherwise, a qualified shop can go through these steps quickly.
- Confirm the code and check for companions. Scan for all stored and pending codes. Note any other throttle or pedal codes (P0120–P0229 range). Multiple related codes often point straight to a failing throttle body or pedal sensor.
- Check freeze frame data. Look at RPM, throttle position, and vehicle speed when P0228 set. If it happens at key-on or idle, suspect wiring or sensor. If it happens under acceleration, suspect intermittent connection or internal sensor failure.
- Visual inspection of throttle body and pedal area. Inspect connectors for corrosion, broken locks, bent pins, or oil intrusion. Check the harness where it flexes or rubs on brackets. Repair any obvious damage before going deeper.
- Monitor live data for TPS/APP signals. With key on, engine off, watch the TPS and APP sensor A/B/C values. Slowly press and release the pedal. You’re looking for smooth, linear changes without sudden jumps, dropouts, or one sensor stuck high (often above 4.5–5.0 volts or 90–100% when the others are low).
- Compare sensor C to sensors A and B. The three signals should track each other in a predictable pattern. If Sensor C is always higher than the others or pegged at maximum, that’s your problem circuit.
- Check reference voltage and ground. With a multimeter, verify 5V reference and good ground at the throttle or pedal connector. A missing ground or shorted 5V line can cause high signal readings.
- Test signal wire integrity. With the connector unplugged, check resistance from the sensor C signal pin to the ECU connector. Look for high resistance, shorts to power, or shorts to other sensor wires.
- Wiggle test. While watching live data, gently move the harness and connectors. If the TPS/APP C signal spikes high when you flex the harness, you’ve likely found a broken wire or poor connection.
- Component substitution. If wiring, power, and ground all check out but the signal remains faulty, the throttle body or pedal assembly is usually at fault. Replacing the suspect component and performing any required relearn is the next step.
- Recheck and road test. Clear codes, perform a road test under similar conditions to when the code set, and confirm that P0228 does not return.
Pro tip: On many modern vehicles, use Mode $06 or manufacturer-specific data to see throttle sensor test results. This can reveal marginal sensors that haven’t fully failed yet but are drifting out of spec.
Possible Fixes & Repair Costs
The exact repair depends on what you find during diagnosis, but most P0228 fixes fall into a few categories. A simple connector cleaning or wiring repair may only cost you some time and a few dollars in supplies. A replacement throttle body typically runs $250–$700 parts and labor at an independent shop, while an accelerator pedal assembly is often $150–$400 installed. If the ECU itself is bad (rare), you could be looking at $600–$1,200 or more including programming. Costs vary with vehicle make, part availability, and local labor rates.
- Clean and tighten throttle body and pedal connectors; apply dielectric grease.
- Repair or replace damaged wiring or terminals in the TPS/APP circuit.
- Replace the throttle body assembly with integrated TPS sensors.
- Replace the accelerator pedal assembly if its internal sensors are faulty.
- Perform throttle/idle relearn or pedal relearn procedure with a scan tool.
- In rare cases, replace or reprogram the ECU/PCM after confirming it’s defective.
Can I Still Drive With P0228?
You can usually drive short distances with P0228, but it’s not recommended for long trips or heavy traffic. The car may go into limp mode without warning, limiting speed and power. That can be dangerous when merging, passing, or crossing intersections. If the vehicle is already in reduced power mode, drive gently to a safe location or repair facility. Avoid towing heavy loads or high-speed driving until the issue is fixed.
What Happens If You Ignore P0228?
Ignoring P0228 can lead to worsening drivability, frequent limp mode events, and possible stalling at inconvenient or unsafe times. Long term, running with faulty throttle data can stress other components and mask new problems because the check engine light is already on. It’s a code you should treat as a priority, not something to live with.
Related Codes
- P0229 – Throttle/Pedal Position Sensor/Switch “C” Circuit Intermittent
- P0227 – Throttle/Pedal Position Sensor/Switch “C” Circuit Low
- P0226 – Throttle/Pedal Position Sensor/Switch “C” Circuit Range/Performance
- P0225 – Throttle/Pedal Position Sensor/Switch “C” Circuit
- P0224 – Throttle/Pedal Position Sensor/Switch “B” Circuit Intermittent
- P0223 – Throttle/Pedal Position Sensor/Switch “B” Circuit High
- P0222 – Throttle/Pedal Position Sensor/Switch “B” Circuit Low
- P0221 – Throttle/Pedal Position Sensor/Switch “B” Circuit Range/Performance
- P0220 – Throttle/Pedal Position Sensor/Switch “B” Circuit
- P0219 – Engine Overspeed Condition
Key Takeaways
- P0228 means the ECU sees an abnormally high signal from throttle/pedal position Sensor C.
- Common symptoms include limp mode, poor acceleration, and unstable idle.
- Most causes are sensor failure, wiring issues, or a bad throttle body or pedal assembly.
- Proper diagnosis with a scan tool and multimeter prevents unnecessary parts replacement.
- Driving with P0228 is risky; fix it soon to avoid unsafe power loss or stalling.
Vehicles Commonly Affected by P0228
P0228 shows up most often on modern drive-by-wire vehicles from manufacturers like GM (Chevrolet, GMC, Buick, Cadillac), Ford (Ford, Lincoln), Chrysler/Dodge/Jeep/Ram, Toyota and Lexus, Nissan and Infiniti, Hyundai and Kia, as well as Volkswagen, Audi, and some BMW models. You’ll see it on sedans, SUVs, and pickup trucks alike, especially those with electronic throttle bodies that have a few years and miles on them. Fleet vehicles and work trucks that see heavy use are also frequent visitors to the shop with this code.
FAQ
Can I clear P0228 and keep driving if the car seems fine?
You can clear the code, but if the underlying problem isn’t fixed, P0228 will usually come back, often at the worst possible time. Use clearing the code only as part of diagnosis or to confirm a repair, not as a permanent solution.
Is P0228 caused by a bad throttle body every time?
No. A bad throttle body is common, but not guaranteed. Wiring issues, a faulty pedal sensor, poor grounds, or connector corrosion can all trigger P0228. That’s why testing power, ground, and signal before buying parts is important.
Can a dirty throttle body cause P0228?
A dirty throttle body by itself usually causes idle and performance issues rather than a direct P0228. However, if carbon buildup makes the throttle plate stick or move erratically, it can contribute to abnormal sensor readings and related codes. Cleaning is a good first step if buildup is heavy.
How do I know if it’s the pedal sensor or the throttle body?
Use live data on a scan tool. If the APP (pedal) signals look clean and consistent but the TPS (throttle) Sensor C is off, suspect the throttle body. If the pedal signals are erratic or one channel is stuck, the pedal assembly is more likely. Wiring checks between each component and the ECU help confirm it.
Do I need a throttle relearn after fixing P0228?
On many vehicles, yes. After replacing the throttle body or sometimes the pedal assembly, you must perform a throttle or idle relearn with a scan tool or a specific key-on/off procedure. Skipping this step can leave you with rough idle, poor response, or the code returning.