Throttle Position Sensor Range/Performance Problem
Throttle Position Sensor (TPS) voltage is out of expected range.
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What it means (plain English)
The Throttle Position Sensor measures how open the throttle plate is, and it sends this info to the engine computer to control power output. If the sensor sends a signal that's too high or too low, the computer thinks something's wrong and turns on the check engine light.
What the computer is actually seeing
The engine control module (ECM) expects a voltage signal from the TPS that ranges from about 0.5V (closed) to 4.5V (fully open). If it sees a voltage outside of this range, especially when the throttle is in a normal position, it triggers the P1571 code.
What a healthy reading looks like
TPS should output between 0.5V and 4.5V; at idle, expect around 0.5V - 0.7V and at wide-open throttle, around 4.0V - 4.5V.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the wiring and connector at the Throttle Position Sensor (TPS) for damage or corrosion. Fix any issues found.
- 22. Use a multimeter to measure the voltage at the TPS while moving the throttle. Confirm it ranges from 0.5V (closed) to 4.5V (open). If not, replace the TPS.
- 33. Check the throttle body for dirt or carbon buildup. Clean as necessary and recheck the TPS voltage.
- 44. If the TPS checks out and the throttle body is clean, check the ECM for any software updates or errors that may need addressing.
- 55. If all else fails, consider testing the ECM, though this is less common.
Common causes
- Faulty Throttle Position Sensor
- Damaged wiring or connectors
- ECM software issues
- Throttle body misalignment or debris
- Signal interference from other sensors
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It can still be drivable, but performance may be reduced and it could lead to lower fuel efficiency.
Will this code come back after I reset it?
If the underlying issue isn't fixed, yes, the code will likely return.
Why does this code sometimes pair with P0120?
P0120 is related to TPS circuit malfunction; if the sensor fails, it can trigger both codes due to wiring or sensor issues.
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