Ignition and misfires code
P0325: Knock sensor circuit fault (bank 1)
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 knock sensor is a small microphone bolted to the engine block that listens for pinging. The computer found a fault in its wiring or signal, so it cannot hear knock on the cylinder 1 side. To protect the engine, it pulls back spark timing, which costs some power.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Failed knock sensor
Safe for normal driving, but avoid hard acceleration and use good fuel until fixed.
What you may notice
- Reduced power
- Pinging or knocking sound
- Poor mileage
- Check-engine light on
Common causes, most likely first
- Failed knock sensor
- Damaged wiring
- Loose sensor
- Corroded connector
- Computer fault
Check this first
Look at the wiring and plug on the knock sensor for oil, cracked insulation or a loose connector. The sensor sits in the block where heat and oil attack the wires. Also ask whether the sensor bolt was recently touched.
Other repairs that sometimes fix P0325
| Repair | Typical range, Boston |
|---|---|
| ECU / engine control module replacement | $430 to $2,350 |
| CAN bus wiring repair | $190 to $1,275 |
| Spark plug replacement | $95 to $580 |
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).
P0325 questions
Why is the sensor hard to reach?
On many V-type engines it sits in the valley under the intake manifold, so reaching it means taking parts off. The part is cheap, but the labor can be the larger share of the bill.
Can I keep driving?
Gently, yes. Without a working sensor the computer holds timing back as a safeguard, so the car feels weaker. Avoid towing and hard acceleration until it is repaired.
Does it affect fuel economy?
Slightly. Because timing is held back for safety, the engine is not as efficient and may use a little more fuel. It is rarely noticeable on a short drive but adds up over weeks.
How much does it cost to fix P0325?
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
- P0300: Random or multiple cylinder misfires
- P0301: Cylinder 1 misfire
- P0340: Camshaft position sensor circuit fault
- P0171: Engine getting too much air or too little fuel (bank 1)
More ignition and misfires 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.