Engine code
P2138: Accelerator pedal sensors disagree
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $0 | $0 |
| Labor: 0.5 to 1.5 hours × $125 to $175 an hour | $63 | $263 |
| Fees: shop supplies, disposal, diagnostics | $0 | $25 |
| Total, rounded | $60 | $290 |
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, diagnostic scan (check engine light). Which repair your car needs depends on a proper diagnosis.
The gas pedal on a modern car has two sensors that read how far you have pushed it. This code means they do not agree with each other. Because the pedal controls the throttle by wire, the computer limits engine power until it can trust the signal again.
- Safe to drive?
- Short trips only
- Most common cause
- Failed pedal assembly
Drive carefully; the car may have reduced power and slow response.
What you may notice
- Limp mode
- Poor acceleration
- Rough response
- Warning light on
Common causes, most likely first
- Failed pedal assembly
- Wiring problem
- Poor connection
- Moisture at the plug
- Computer fault
Check this first
Check under the dash for a loose pedal plug, and clean up any spilled drinks or dirt near the pedal. Wiggle the plug while the key is on and watch for any change. A damp or loose plug is a common cause.
Other repairs that sometimes fix P2138
| Repair | Typical range, Boston |
|---|---|
| Throttle body replacement | $300 to $940 |
| ECU / engine control module replacement | $430 to $2,350 |
| CAN bus wiring repair | $190 to $1,275 |
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).
P2138 questions
Can I replace the pedal myself?
Often yes. The assembly is usually held on by a few bolts and a plug, and replacement is straightforward with basic tools. Use the correct part for your car, because the sensors are matched to the computer.
Is it the throttle body?
For this code, the pedal is far more likely than the throttle body. The throttle sensors have their own codes, so a shop reading both will know which side has the problem before buying anything.
Will it clear on its own?
Rarely. If the cause is moisture or a loose plug it may come and go, but a worn sensor stays bad. If the light clears, the problem can return, so watch for slow response or limp mode.
How much does it cost to fix P2138?
The most common fix, diagnostic scan (check engine light), has a typical range of $60 to $290 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
- P2135: Throttle position sensors disagree
- P0121: Throttle position reading doesn't match
- P0122: Throttle position signal too low
- P0507: Engine idle higher than expected
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.