MajorVery commonEngine

Honda Accord: N22A1 EGR Valve and Inlet Manifold Carbon Soot Blockage

N22A1 EGR Valve and Inlet Manifold Carbon Soot Blockage is a very common engine fault on the Honda Accord on the 2004–2008 cars, and we rate it major. Putting it right costs $450 to $1,100 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 55 documented faults on the Honda Accord.

Vehicle: Honda Accord
Engine: 2.2L
Years: 2004–2008
Fuel: diesel
System: Engine

This page covers the Honda Accord as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Honda Accord faults55 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Intake manifold or EGR valve yet. We would rather show none than show a picture of a different part.

What goes wrong

The N22A1 2.2-litre i-CTDi diesel recirculates exhaust gas through an EGR valve that progressively deposits carbon soot inside the inlet manifold and on the intake valves. On vehicles used predominantly in urban stop-start driving, blockage can occur well before 150,000 km. Symptoms escalate from rough idle to significant power loss and ultimately to limp-home mode. The EGR valve itself seizes in partially-open positions, disrupting fuelling. Full cleaning requires inlet manifold removal and is labour-intensive.

What you would notice

Rough or lumpy idle, particularly when cold
Progressive loss of power and turbo response, especially below 2000 rpm
Heavy black or grey smoke from exhaust at idle or on light throttle
MIL illuminated with P0401 or P0404 EGR flow codes
Engine entering limp-home mode (restricted to approximately 2500 rpm) in severe cases

How to check it

Where to look. EGR valve on left side of engine block, inlet manifold passages, intake ports on cylinder head

Inspect the air intake pipe between intercooler and throttle body for heavy oily soot deposits.
Scan for fault codes P0401 (EGR flow insufficient) or P0404 (EGR circuit range).
Check for blue-grey smoke at idle.
If a workshop inspection is possible: Remove the inlet manifold inspection plug or disconnect the EGR pipe to check for coke buildup.

Parts involved: Intake manifold, EGR valve.

What it costs to put right

$450 to $1,100 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the EGR valve or inlet manifold ever been cleaned or replaced?”
“Is the vehicle used mainly for short urban trips, or mostly motorway driving?”
“Are there any engine warning lights currently present or recently cleared?”

Now check the Honda Accord you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Honda Accord buyer questions

Is n22a1 egr valve and inlet manifold carbon soot blockage serious on a Honda Accord?

We rate it major and very common on the Honda Accord. The N22A1 2.2-litre i-CTDi diesel recirculates exhaust gas through an EGR valve that progressively deposits carbon soot inside the inlet manifold and on the intake valves. On vehicles used predominantly in urban stop-start driving, blockage can occur well before 150,000 km. Symptoms escalate from rough idle to significant power loss and ultimately to limp-home mode. The EGR valve itself seizes in partially-open positions, disrupting fuelling. Full cleaning requires inlet manifold removal and is labour-intensive.

How much does it cost to fix on a Honda Accord?

$450 to $1,100 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Honda Accord years are affected?

Our research records this fault on the 2004–2008 Honda Accord. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Inspect the air intake pipe between intercooler and throttle body for heavy oily soot deposits. Scan for fault codes P0401 (EGR flow insufficient) or P0404 (EGR circuit range). Check for blue-grey smoke at idle. If a workshop inspection is possible: Remove the inlet manifold inspection plug or disconnect the EGR pipe to check for coke buildup. Look here: EGR valve on left side of engine block, inlet manifold passages, intake ports on cylinder head