Emissions code
P0402: Exhaust recirculation flow too high
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $60 | $350 |
| Labor: 0.8 to 2.2 hours × $125 to $175 an hour | $100 | $385 |
| Fees: shop supplies, disposal, diagnostics | $0 | $20 |
| Total, rounded | $160 | $760 |
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, egr valve replacement. Which repair your car needs depends on a proper diagnosis.
The computer measured more exhaust gas flowing into the intake than it asked for. On this code the EGR valve is most likely stuck partly open, usually from a carbon deposit holding it off its seat, so exhaust keeps leaking in when it should not, especially at idle.
- Safe to drive?
- Short trips only
- Most common cause
- EGR valve stuck partly open from carbon
Usually drivable, but a valve stuck open can cause stalling at stops, so be careful in traffic.
What you may notice
- Rough idle
- Stalling when you stop
- Hesitation on pull-away
- Check-engine light
Common causes, most likely first
- EGR valve stuck partly open from carbon
- Failed EGR position sensor
- Vacuum control problem on older cars
- Wiring fault at the valve
Check this first
Ask whether the valve can be cleaned before buying a new one, and whether the vacuum lines to it were checked.
Other repairs that sometimes fix P0402
| Repair | Typical range, Boston |
|---|---|
| Diagnostic scan (check engine light) | $60 to $290 |
| Vacuum leak repair | $100 to $530 |
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).
P0402 questions
What does the EGR valve do?
It sends a small amount of exhaust back into the engine to keep combustion cooler and cut smog gases. It opens mostly at cruise, and it should stay shut at idle and during cold starts.
Why does it stall at stops?
A valve stuck open lets exhaust into the intake when the engine needs clean air at idle. The mix gets diluted, and the engine runs rough or dies when you come to a stop.
Will cleaning hold up?
Sometimes, but if carbon builds fast, the real cause may be oily intake air from the PCV system or a weak valve. Ask the shop whether they checked why the valve got dirty.
How much does it cost to fix P0402?
The most common fix, egr valve replacement, has a typical range of $160 to $760 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
- P0401: Exhaust gas recirculation flow too low
- P0404: Exhaust recirculation system not working as commanded
More emissions 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.