Engine code
P0123: Throttle position sensor A reads high
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $180 | $600 |
| Labor: 1 to 1.8 hours × $125 to $175 an hour | $125 | $315 |
| Fees: shop supplies, disposal, diagnostics | $0 | $25 |
| Total, rounded | $300 | $940 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in Boston, $31.54 an hour, times 4 to 5.5 to cover what a shop bills (overhead, tools, insurance, profit). Parts are a band from budget aftermarket to the manufacturer part. Full method.
Not a repair shop, estimates only. Typical range, estimate. Not a quote. Your car, parts and shop change the number.
This is the range for the most common fix, throttle body replacement. Which repair your car needs depends on a proper diagnosis.
The throttle position sensor tells the computer how far the throttle is open. Sensor A is sending a voltage that is higher than the throttle could ever produce, which usually means the sensor failed, its ground is broken or the throttle body is worn. The computer limits power until it trusts the reading.
- Safe to drive?
- No, get it looked at first
- Most common cause
- Failed throttle position sensor
The car may drop power or surge unexpectedly. Avoid driving until it is checked.
What you may notice
- Reduced power or limp mode
- Surging
- Rough idle
- Check-engine light
Common causes, most likely first
- Failed throttle position sensor
- Throttle body wear
- Damaged wiring or sensor ground
- Dirty throttle body
Check this first
Have the shop look at the live throttle readings on a scan tool. The values should rise smoothly as the pedal moves.
Other repairs that sometimes fix P0123
| Repair | Typical range, Boston |
|---|---|
| Throttle body cleaning | $85 to $210 |
| Diagnostic scan (check engine light) | $60 to $290 |
Before you pay
- Ask the shop what test showed this part is the cause, not just that the code appeared.
- Ask for parts and labor listed separately, and for the hours.
- Ask for a written OK before any extra work. Massachusetts rules require written authorization before repairs.
Got a quote already? Check it against the range. Want to see if your car has a recall tied to this problem? Check recalls by VIN.
Need to read a code yourself? OBD-II scanners on eBay (affiliate link, disclosure).
P0123 questions
Is the sensor sold separately?
On many cars the sensor is built into the electronic throttle body, so the whole part is replaced. Some older cars sell the sensor alone, so ask the shop what applies to yours.
Why does it surge?
A false high reading makes the computer think the throttle is open more than it is, so it may add fuel or change idle at the wrong times. That shows up as surging or an uneven idle.
Can I drive it?
It is better not to. An unexpected loss of power in traffic is a safety risk. If you must drive, keep trips short and in low-speed areas, and leave extra room around you.
How much does it cost to fix P0123?
The most common fix, throttle body replacement, has a typical range of $300 to $940 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
Related codes
More engine codes
Code meaning written in our own words. Some codes mean different things on different makes, so check your scan tool or manual. Not a repair shop, estimates only.