Hi Guys,

Been lurking here for about three years. Never had to post or ask questions because I have always been able to find the answers by searching here. Now I'm stumped and thought I would ask for help.

Car: 1998 Honda Accord LX, 4 cyl. (non ABS)
Mileage: 231,000
Car burns a ridiculous amount of oil (1 quart/month), but runs like a top.

Code: P1491 EGR Lift Insufficient Detected
Possible Cause:
Open or short circuit condition
Poor electrical connection
Failed EGR Valve

What I have done so far:

1. Removed throttle body and intake plenum. Cleaned egr port on plenum.
2. Filled EGR passage with carb cleaner and reemed it out with coat hanger and shop vac. Passage appears clear and I can blow air through it. However, intake plenum looks worse than the BP oil spill. Will clean it this weekend.
3. Soaked EGR Valve in carb cleaner and scrubbed clean with toothbrush inside and out.
4. Tested EGR Valve after cleaning by disconnected 6 prong plug and running a wire from the positive battery terminal to the No. 4 pin and a ground wire to the No. 6 pin. Heard a loud click indicating that the valve is opening/working.
5. Used a multimeter to test the connecter plug. Turned key to On, inserted multimeter probes into wire harness. Read 12V. Is that good?

Since doing this, I’ve driven the car over 100 miles and the code will not clear.

Do I need to clean the passages that I highlighted in yellow? Has anyone ever seen clogged passages coming from the exhaust side (near part 25)? I’m not sure where the exhaust gases are originating from.

I'm also wondering if the aftermarket EGR Valve that is on the car now is simply not as 'strong' as the OEM one. The one on there now is made in Canada. Unless the Siemens one on there now is an OEM part. I don't know.

Any other input would be appreciated. I hate the thought of having my mechanic just throw more parts at the car without fixing the problem.

 

the factory diagnosis is fairly extensive, but it sounds like you've covered it pretty well.
at this point, it's either the EGR valve or the ECM. i'm leaning towards the valve, because the code is valve malfunction code and not a system code. anotherwords, no matter how well you clean the passages if the valve is not lifting the proper amount according to the ECM it won't matter.

 

The exhaust gasses originate from the passage in the cylinder head, your yellow highlight. When I cleaned the EGR on my F23 that passage was clear. From that point on the intake manifold to the round hole on the EGR valve base was gunked up, as well as from the square hole on the valve base to the plenum. Those passages need to be open and clean.

I'm not familar with the all-electric 6th Gen EGR function. The fact that it clicks probably doesn't indicate that the lift sensor is operating correctly. It could be a bad EGR valve, bad wiring, or a bad ECU. I have a PDF of the Fuel & Emissions FSM but it's in Spanish; a piece of it below. Maybe someone else can point you to an English version or offer troubleshooting advice. But EGR valves are pretty reliable and they're probably pretty cheap at the junkyard, like $10 or so. It might worth just swapping parts for the cost of a used valve and new gasket.

 

Dr. Drivability did while I was typing.

 

Thanks Dr.

I'm hoping it's the valve and not the ECM. Since I'm getting the "Insufficient Lift" code and not the "Insufficient FLOW" code, I'm hoping that I can just swap in a new valve. Is it possible that the amount of oil that the car burns has killed the EGR valve?

If the ECM was bad would the code be different?

 

Thanks for the reply.

 

no, the code is for the valve or the ECM depending on how the testing pans out.

 

Thanks. Dr.

Is there a way for me to rule out the ECM? If there was a problem with the ECM, would it still be able to throw the p1471 code?

I've read countless threads on this p1471 code, but most of them seem to trail off or end abruptly with no updates. The OP's seem to disappear from the internet... I'd like to have a fully documented thread on this issue for the 1998-2002 accord I-4's.

 

This should be simple electrical fault detection by ECM, but I could not find confirmation. On earlier models w/ vacuum actuation, the ECM looked for a change in manifold pressure to confirm valve was lifting on command. It may check both MP and electrical circuit.

You could check the continuity of the actuation circuit at the ECM/Harness connection. If the wire/s check OK at that point, the ECM is likely fault.

I had this experience twice on different distributor electrical sensor faults that were reported by ECM on my 94EX. In both cases ECM turned out to be the problem.

good luck

 

The ECU tells the EGR valve to open. A lift sensor in the EGR valves tells the ECU if the EGR valve is open when it's supposed to be. So insufficient lift can be:

• the EGR valve isn't actually opening when it's supposed to
• the lift sensor isn't sensing that the valve is open when it actually is
• ECU is out of its mind
• open or shorted wiring between the ECU and the valve

I'm not a fan of shotgunning parts to diagnose, but the valve is so easy to get replace, a used OEM valve is cheap, and it might be a crappy aftermarket valve on there anyway...