P1491 and P0172

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billyfieldman, Jul 12, 11:01pm
For close to one year since they cleaned the RACV valve, no further problems. Then two days ago, the CEL came up and they got the P1491 and P0172 again.

Honda removed the EGR to show me carbon built up and suggest replacing it at a cost of almost $600. But they still wouldn't guarantee that would solve the problem, just that they are 90% sure the EGR is the cause. The impression I get is that it is trial and error approach.

I'm thinking just cleaning the EGR and possibly the RACV to see if the problem goes away.

Is that the right way to go?
billyfieldman, Jul 12, 11:19pm
They also suggested to blank off the EGR. Is that a good idea? Wouldn't that damage the catalytic converter?
thejazzpianoma, Jul 13, 12:15am
What fuel and oil are you running it on?
billyfieldman, Jul 13, 2:14am
95 petrol and Mobil Super 2000 10w 40. Would this cause those problems?
snoopy221, Jul 13, 2:22am
it's an 02 (2002) so egr can legally be removed.

While it may be acceptable as an economy/emissions device on a brand new vehicle with age and mileage rebreathing the crap that an engine exhausts is not a good plan
intrade, Jul 13, 3:33am
no thats fine .
thejazzpianoma, Jul 13, 7:00am
Should be fine but I would swap out the Mobil Super for a full Synthetic oil next time. How is oil consumption?
billyfieldman, Jul 13, 7:25pm
They tried to blank it off today but it's more complicated than just putting a plate. According to them, the ECU insisted on operating the EGR. So that is aborted.

Is the carbon build up in EGR due to fuel too rich or is it the other way?
billyfieldman, Jul 13, 7:33pm
Between oil changes (10,000km) oil drops from near max to slightly above min.
thejazzpianoma, Jul 13, 10:44pm
They should have checked the fuel trim to ensure that was correct. Potentially rich fuel is more likely to cause the problem. I am a bit concerned that they were expecting to just block off the EGR without the computer turning on the check engine light etc. That's pretty basic stuff on a modern car.

I would suggest you get a second opinion. Have someone check the fuel trims (quick and easy). Then if all is well I think I would put a brand new EGR on (not just a clean as sometimes that doesn't last). Then do the swap to full synthetic oil.

The other way around it is to have a look on the net and see what's available in terms of a remap with egr delete to disable the EGR via the computer. A local specialist could do that but it could be pricy. Sometimes you can buy the software and cable online and either do it your self (BUT BE CAREFUL) or get a mechanic to do it for you.

THis might make it a $100 job rather than a $800+ job.

The catch with this whole thing is it is an older car that's not worth much, plus assuming it's auto they are not a long life trans so it may have limited life left anyway.

Failing that, just learn how to remove the EGR and clean it yourself. Often they are easy enough to get at (each engine is different) and if yours is an easy one it might just be a half hour annual maintenance task for you.
thejazzpianoma, Jul 13, 10:48pm
The other thing on my mind is that if the EGR is blocking up so quickly, what state is the catalytic converter in? The cat is like a very very fine honecomb that passes the exhaust gasses through. They will block and also overheat and crack if too much muck gets introduced.
thejazzpianoma, Jul 13, 10:51pm
What engine is in the accord OP?
It might only be a $50 part ordered online, we could take a look and see how tricky it is to get to. If it's in an easy place you are really just looking at a couple of bolts and a connector. Throwing a new one at it every couple of years might be an option if everything else looks ok.
thejazzpianoma, Jul 13, 11:01pm
Had a quick look online, it looks like at least one of your engine options has a fairly restrictive EGR port (as in a passageway leading to the EGR not the EGR itself) which may also be blocked. They may or may not have cleaned this last time.
billyfieldman, Jul 14, 5:00am
It's F23a engine.
thejazzpianoma, Jul 14, 6:27am
How handy are you with a spanner billyfieldman?
billyfieldman, Jul 14, 11:57pm
Not very handy unless it's in an easily accessible place.

They cleaned the EGR today morning. If CEL doesn't come on anymore next few days, would get the IACV cleaned too.
thejazzpianoma, Jul 15, 12:01am
Had a quick look, really want to take the intake off and clean the passage from what I can see with that motor.

If it comes back on I would suggest watching a couple of youtube videos on the procedure and see what you think. Otherwise just order a new egr and get someone to fit it. Ebay, alibaba etc should be fine for an old car like that and like I said about, expect to pay around $50.

I would suggest using another garage as that they are not sounding very competent at all.
billyfieldman, Aug 29, 10:16pm
2002 Honda Accord had been idling rough. Once it even stalled when stopped at the traffic lights. Thought it was old battery and spark plugs, so had them replaced last week. Still rough when idling.

But yesterday got the check engine light on the dashboard. Went to the garage that did the battery and plugs to read the codes. Mechanic said the codes indicate problems with EGR and fuel system. He cleared the codes and said if the check engine light comes on again, to bring the car in.

Should I bring it to a Honda dealership for a diagnosis. Is it true that dealership scanners are able to get more information out of the car's computers?
franc123, Aug 29, 10:25pm
Yes they can extract more information, but in this case it probably is a sticking or dying EGR valve, they are known for it. Valves that are open when they shouldn't be will certainly cause rough idle and possibly log AFM or 02 sensor codes.
kingfisher21, Aug 30, 2:39am
As above, 1491 is EGR Insufficient Lift and 0172 is Too Rich, more than likely related to the EGR fault.
thejazzpianoma, Aug 30, 5:09am
Deal with this sooner rather than later as it's also very hard on your expensive catalytic converters.
intrade, Aug 30, 5:25am
billyfieldman, Sep 7, 7:20pm
CEL came on and brought the car to Honda. They only got one code P0172 Fuel too rich.

They checked and found that when car is warm , during idle, rough and slightly jerks. If rev the engine then take foot off accelerator, the rpm goes all the way down and sometimes stall. So they cleaned the idle air control.

Idle improves slightly but still subtlely jerks at traffic lights but doesn't stall. No CEL so far.

They are not sure what is causing this because many causes.
intrade, Sep 7, 11:33pm
well did they look at fueltrims?
and did you ring the guy i told you ?
and what tool did the honda place use?
billyfieldman, Sep 8, 12:45am
Haven't called the guy yet. Honda is just 15 minutes away from work place so gave them a try first.

They just said their scanners did not pick up anything that could cause this. According to them unfortunately P0172 has many causes. Never mentioned fueltrims.