OBD Code P0228: Throttle/Petal Position Sensor/Switch C Circuit Low Input

Q: What does OBD code P0228 mean?

Throttle/Petal Position Sensor/Switch C Circuit Low Input. The throttle pedal position sensor is sending a voltage signal that's too low to the engine computer, like a dimmer switch stuck at the bottom position. The ECU can't properly read how far you're pressing the gas pedal.

Q: What are the symptoms of fault code P0228?

Check Engine Light illuminated, Engine hesitation or poor acceleration response, Limp mode or reduced engine power

💬

What This Actually Means

In plain language — no jargon

The throttle pedal position sensor is sending a voltage signal that's too low to the engine computer, like a dimmer switch stuck at the bottom position. The ECU can't properly read how far you're pressing the gas pedal.

⚡

Symptoms You May Notice

3 known symptoms for this code

Check Engine Light illuminated

Engine hesitation or poor acceleration response

Limp mode or reduced engine power

🔬

How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors the analog voltage output from the throttle position sensor (TPS) or electronic pedal sensor as it ranges from idle to full throttle. The sensor voltage should increase proportionally as the pedal is pressed; when voltage stays abnormally low, the ECU logs a fault. This low-voltage condition prevents proper fuel delivery and ignition timing adjustments.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
TPS Voltage	0.5V to 4.5V (idle to WOT)	Below 0.2V or stuck low
Voltage Transition	Smooth, linear increase with pedal movement	No change or erratic low readings

🔧

Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

Electrical connectors and wiring harness

Inspect and clean the throttle sensor connector and wiring for corrosion, loose pins, or damaged insulation.

2

Throttle Position Sensor (TPS) or Pedal Position Sensor

Replace the sensor if voltage remains low after connector inspection and cleaning.

3

ECU or PCM reprogramming/replacement

If voltage reads normal but fault persists, the ECU may need reprogramming or replacement.

⚠️

When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code P0228 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.

🔄

How to Clear Code P0228

What happens after you fix the fault

Once the fault is repaired, P0228 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.

The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.

✅ Safe to Clear When

Fault has been diagnosed and repaired
You want to confirm the repair worked
Code appeared after a sensor was cleaned

⚠️ Do Not Clear When

Preparing for an emissions/PUC test
Root cause is still undiagnosed
Check engine light is flashing

Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.