Emissions code
P0404: Exhaust recirculation system not working as commanded
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 commanded the EGR valve to open to a set position and the actual position or flow does not match. The valve may be stuck, coated in soot, or the passages behind it may be partly blocked. The mismatch sets a performance code instead of a flow-high or flow-low code.
- Safe to drive?
- Short trips only
- Most common cause
- Carbon buildup in the valve
You can drive for a short time. Left alone, it can cause pinging under load and a rough idle.
What you may notice
- Rough idle
- Pinging or knocking when accelerating
- Slightly worse fuel economy
- Check-engine light
Common causes, most likely first
- Carbon buildup in the valve
- Clogged EGR passage in the intake
- Failed valve motor or solenoid
- Faulty position sensor
Check this first
Ask what the valve position reading looks like on a scan tool while it is commanded to open.
Other repairs that sometimes fix P0404
| Repair | Typical range, Boston |
|---|---|
| Diagnostic scan (check engine light) | $60 to $290 |
| Throttle body cleaning | $85 to $210 |
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).
P0404 questions
Is a clogged passage common?
Yes, on higher-mileage engines. Carbon can narrow the passage in the intake, and cleaning it adds labor because parts have to come off. A clean valve into a clogged passage will fail again.
Does it cause damage?
Over time, higher combustion heat can cause pinging, and that wears the engine. A repair within a few months is wise. A short delay will not harm anything immediately.
Does it pass emissions?
The light being on usually fails the check, because most programs reject any car with an active check-engine light. The repair itself helps the car pass, so plan on it before the test.
How much does it cost to fix P0404?
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
- P0402: Exhaust recirculation flow too high
- P0403: Exhaust recirculation valve control circuit problem
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.