P0123
Fix within a few daysThe engine computer detects a higher-than-expected voltage signal from the Throttle Position Sensor (TPS) or Pedal Position Sensor (PPS) 'A' circuit.
Code P0123 means your engine computer detects a high voltage signal from the throttle position sensor. Common causes: Faulty TPS (70%), wiring issues (25%). Drivability: Limit driving, fix within a few days. Repair cost: $30-$150 DIY, $130-$450 professional.
Can I Drive With P0123?
Limit driving, fix within a few days
Essential trips under 10 miles, avoid highways and heavy traffic. Be prepared for sudden power loss or stalling.
Stop driving immediately if: Vehicle stalls frequently, enters limp mode consistently, or has no throttle response.
Symptoms of P0123
- 1Engine hesitation or stumbling during acceleration
- 2Rough or erratic idle
- 3Lack of power or no acceleration
- 4Vehicle enters 'limp mode' (reduced power, limited speed)
- 5Check Engine Light is on
- 6Vehicle stalls unexpectedly
Common Causes of P0123
Parts most likely causing this code, ranked by probability
The sensor itself is faulty, sending an incorrect high voltage signal to the engine computer.
70% of P0123 cases are fixed by replacing this part
A short to voltage, an open circuit, or corrosion in the wiring or connector causes the engine computer to read a high signal.
25% of P0123 cases are fixed by repairing wiring or connectors
Internal damage to the engine computer's TPS input circuit causes it to misinterpret the sensor's signal.
5% of P0123 cases are fixed by replacing the ECM/PCM
Check These First (Before Buying Parts)
- Visually inspect the TPS/PPS sensor and its electrical connector for any obvious damage, corrosion, or loose wires.
- Ensure the throttle body plate moves freely and is not sticking (if applicable to your vehicle's design).
How to Diagnose P0123
- 1Visually inspect the TPS/PPS sensor and its wiring for damage, corrosion, or loose connections.
- 2Check the TPS/PPS connector for bent pins or signs of moisture.
- 3Using a multimeter, test the voltage output of the TPS/PPS at various throttle positions (key on, engine off).
- 4Check for continuity and shorts in the TPS/PPS wiring harness between the sensor and the engine computer.
- 5If possible, use a scan tool to monitor the TPS/PPS live data stream to confirm erratic or high voltage readings.
P0123 on Popular Vehicles
Toyota Camry
2002-2011TPS failures are common on these generations, leading to P0123. Symptoms include erratic idle and poor acceleration.
75% fixed by replacing the TPS
Honda Accord
2003-2012Similar to Camry, the TPS can fail, especially with higher mileage. Wiring issues are less frequent but should be checked.
70% fixed by replacing the TPS
Ford F-150
2004-2014With drive-by-wire systems, the TPS is often integrated into the throttle body. P0123 can indicate a fault with the sensor or the throttle body assembly itself.
65% fixed by replacing the TPS (or throttle body)
Frequently Asked Questions
What does P0123 mean?
P0123 indicates the engine computer is receiving a voltage signal from the Throttle Position Sensor (TPS) or Pedal Position Sensor (PPS) 'A' circuit that is higher than its expected range.
Can I drive with P0123?
Limit driving, fix within a few days. This code often causes serious drivability issues like limp mode, stalling, or sudden loss of power, which are dangerous. Avoid highways and long trips.
Will P0123 clear itself?
No, P0123 will not clear itself. The engine computer stores this code because it detects a persistent electrical fault. The underlying issue must be repaired for the code to clear, either automatically after several drive cycles or by using a scan tool.
How do I fix P0123 myself?
Start by inspecting the TPS/PPS sensor and its wiring for visible damage or loose connections. If the wiring looks good, test the sensor's voltage output with a multimeter. If the sensor is faulty, replace it. If the sensor tests good, trace the wiring for shorts or opens.
How much does it cost to fix P0123?
DIY repair costs for P0123 are typically $30-$150 for a new TPS/PPS sensor. Professional repair at a shop costs $130-$450, which includes parts and 1-2 hours of labor.
P0123 keeps coming back - why?
If P0123 keeps returning, the initial diagnosis was incomplete. This indicates a deeper electrical issue like a short in the wiring harness that was missed, or a rare fault with the engine computer itself. Re-check all wiring thoroughly.
Will P0123 fail emissions/smog test?
Yes, P0123 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most jurisdictions, and a faulty TPS/PPS directly impacts engine performance and emissions control.
What's the difference between P0123 and P0122?
P0123 indicates a 'high input' from the TPS/PPS 'A' circuit, meaning the engine computer sees a voltage signal that is too high. P0122 indicates a 'low input' from the same circuit, meaning the engine computer sees a voltage signal that is too low.
P0123 on Toyota Camry?
On Toyota Camry models, P0123 is often caused by a failing Throttle Position Sensor. While less common on newer drive-by-wire systems, older models are known to have TPS failures that trigger this code. Always check the wiring first.
Questions to Ask Your Mechanic
Did you test the TPS/PPS voltage output at various throttle positions?
Good answer: Yes, I used a multimeter and a scan tool to verify the voltage signal is consistently high, even at idle. It's not fluctuating correctly with throttle input.
Have you checked the wiring harness for any shorts to voltage or open circuits?
Good answer: Yes, I performed a continuity test and checked for shorts to power and ground on the TPS/PPS circuit wires. The wiring appears intact and free of shorts.
Repair Cost Estimate
DIY Repair
Parts only
$30-$150
Shop Repair
Parts + labor
$130-$450
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-2 hours
Intermediate - requires basic hand tools and a multimeter for accurate diagnosis. A scan tool is highly beneficial for monitoring live data.
Cost of Waiting
Ignoring P0123 can lead to dangerous driving conditions due to sudden power loss or limp mode. Continued operation with an erratic TPS can also cause incorrect fuel delivery, potentially damaging your catalytic converter ($800-$2,500 repair). A $50 sensor fix now prevents a much larger bill later.
While You're In There...
If you are accessing the throttle body to replace the TPS, cleaning the throttle plate and bore can improve idle quality and throttle response.
A clean air filter ensures proper airflow to the engine, which is critical for accurate sensor readings and overall engine performance.
Tools You'll Need
- Basic hand tools (sockets, wrenches)
- Multimeter
- Scan tool (optional, but highly recommended for live data)
P0123 is a common sensor code. Most repairs involve replacing the Throttle Position Sensor, which is a straightforward job for an intermediate DIYer, and your vehicle's throttle response will be restored.
- Family-owned since 1957
- 990,000+ happy customers
- Fast nationwide shipping
- Easy returns
Your Next Steps
Step 1: Perform a thorough visual inspection of the TPS/PPS sensor and its wiring harness for any signs of damage, fraying, or loose connections. Check the connector for corrosion.
Step 2: If the visual inspection reveals no obvious issues, use a multimeter to test the TPS/PPS sensor's voltage output. Compare readings to your vehicle's service manual specifications.
Step 3: If the sensor tests faulty, replace the Throttle Position Sensor. If the sensor tests good, you will need to trace the wiring for shorts to voltage or open circuits, or consider a rare ECM/PCM fault.