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2002 Pathfinder-Catalytic Converter sucked into engine?

Our 2002 Pathfinder SE with 194,000 miles malfuntioned:
Had it towed to dealer
Dealer says ECM bad (Engine control module)
Says relays also bad
Says brakes are completely worn through
Says spark plugs need to be replaced
Says IAC needs replacing, coolant leaking
We pay $3,400 for repairs.
Drove car off from dealer and it now uses 1 quart of oil per 100 (no, not 1000, 100) miles
Dealer says catalytic converter got sucked into the engine and ruined it.
I ask why do they think the ECM failed at the same time the catalytic converter failed?
They say they had to replace the ECM to figure out what happened?
Now we have a Pathfinder using 1 quart of oil per 100 miles and spent $3,400 for what?
Does any of this make sense?

That is total nonsense.

My opinion, you should never taken it to a dealer, but too late.

Document everything, take it back and see what they say, but also contact Nissan regional headquarters. The contact info should be in your owner’s manual.

edit, stand corrected, Cat Conv could have a part sucked into the engine… sounds weird tho…

That in itself should have been an alarm.

IAC valves don’t leak coolant.

The engine in your Nissan is capable of pulling in the ceramic substrate from the pre-catalytic converter if it should break down.

This is due to the valve over-lap where the exhaust valve is open for a period when the piston is in its intake stroke.

This ceramic substrate destroys the cylinder walls and the engine burns oil.



Thanks Tester. I learned something. It does make sense.

Can you write in your post exactly what was written on the shop orders? You did, I hope, keep your copies?

What was the malfunction?

How much oil was being used before the malfunction?

Like Tester mentioned the exhaust valve is held open briefly on the intake stroke to pull in some exhaust gases. Takes the place of having an EGR.valve.

None. No substantial amount of oil was being consumed prior to the car malfunctioning.

After seeing Tester’s reply, I did some searching and reading on this.

The best I can tell is Nissan’s QR25DE and VQ35DE engines, between 2002-2005, had their variable valve timing set to include EGR functionality. This momentary “pulling in” of some of the exhaust gas worked fine if the pre-cats were in good condition.

However, if anything ever caused the pre-cats to begin to fail, the substrate powder would get sucked back into the combustion chambers, resulting in oil burning.

It’s not clear if the oil burning happened because the substrate powder, in combination with the compression rings, grinded away at the cylinder walls, or if that powder plugged up the oil control rings. I would have thought the former, but when I see meisterben’s comments saying the oil consumption began almost immediately, it makes me wonder if the latter could be happening.

Perhaps a compression test would tell.

Why did you agree to 3200 in repairs to a car worth 2500?
Why didn’t the dealer ask you to consider buying new car?
Or a used car they might have?

The OP’s tale seems to relate a story of both poor maintenance and bad decision-making in regard to the value of the vehicle vs the cost of repairs.

Is this fair to meisterben?
Can you help us see what in his posts indicate poor maintenance?

And we don’t know what the dealer told him that led him to believing the $3400 in repairs would solve his problems. Maybe the dealer told him he’d be good to go with those repairs.

Someone came here sincerely asking for help. Please let’s not kick him while he’s down.


Hmmm…Well, if we assume that the folks at the dealership were being honest (which nobody knows from afar) about the brakes being “completely worn through”, and about the spark plugs being bad, to me that indicates a vehicle that hadn’t been in a mechanic’s shop for a fairly long time. You may wish to disagree.

Rather than trying to “kick” the OP, I am trying to give him/her some food for thought regarding the maintenance of their next vehicle, and about the rationale behind expensive repairs on an old vehicle with a very low book value. You may wish to disagree on that point also.

Maybe for the same reasons millions of others do the same thing. They still like their car, it served them well and maybe this one expensive repair allows them to keep the car for many more years. Or, maybe others are not as rich as you are and don’t want a new monthly car payment or can’t afford one.

I find those questions ridiculous because they are an individual’s decision.

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pcm’s are expensive

I’m guessing those are probably separate problems. The IAC is faulty, and something else is leaking coolant.

As far as the situation in total, with all of those problems noted, it would be difficult for the shop to know where to start first. If they knew beforehand the cat had failed and debris had ended up in the cylinders, I expect they’d have informed the owner before any repairs ensued. But apparently they didn’t know this, so they went ahead & replaced the ECM, fixed the coolant problem, replaced the spark plugs, and the relays, only for the owner to discover the oil usage problem which the shop ascribes to the cat breakdown. No shop is going to let a owner drive a car away with worn through brakes. I feel for the OP, but I don’t see that another shop would likely have done anything differently.

In retrospect, for a 15 year old vehicle with close to 200K that needs a new ECM, has a coolant leak, completely worn out brakes, spark plugs, all that indicates normal preventative maintenance is likely well behind schedule. The best course of action in that situation is probably not to immediately start fixing everything that is known to be broken. Instead basic engine testing is probably the first objective, a compression test, cooling system pressure test, possibly a cylinder leak down test. Whether all that would have resulted in a different outcome however, hard to say. It depends on what those test results were and interpreted.

So what’s the OP to do? hmm … I don’t think laying blame on the shop is going to get the OP anywhere. Probalby best to try to keep the shop on the OP’s side. Ask if it might be possible for a machine shop to fix what’s broken w/ the engine insides. Or what it would cost to replace the main block or the entire engine with a used one from another wrecked.vehicle. the shop might be willing to eat a portion of the cost, given what the OP has already paid. And the OP vehicle does have a new ECM and repaired brakes. There’s the issue of the cat replacement expense to consider still. So it might make more sense to just give up, sell it to a junkyard, and buy another vehicle.

Thanks Kurtwm2010. Your response was spot on for why we decided to have the car repaired. What I don’t understand is the check engine light WAS on for cat converter codes and they did the OTHER repairs and sent us on our way. How could they do this? Here is the original repair order verbatum:

  Owner states acceleration dripped and lost brakes and steering.  Hear something skip prior to stall. Smell inside car.
 Mechanic found out a fuse in the engine was popped which in turn took out the ECM relay.  It was found the fuse had popped due to an internal fail in the ECM which controls the ground.  Replaced 10 amp fuse, ECM relay and ECM completed.
 A check engine light is still on due to cat converter codes.  Initially faulty ECU had stored codes for 02 sensor failure.  New ECU is picking up codes for cat converter and knock sensor failure.  
 Replace faulty IAC Assembly.
 Codes were stored for ICS system, and coolant was leaking from IAC assembly.  Replaced IAC assembly and performed idle air relearn.  Erased codes, car idles and runs and idles fine and no longer leaks from assembly.
 Replace worn and fuel fouled spark plugs.
 Upon checking for spark on primary concern it was found that the plugs were fouled, recommended replacement.  Replaced spark plugs completed.

Oil and filter change.
This is the “meat” of the repair order.

Thanks, you guys are awesome!

Not sure I understand your question. The “meat” of the repair was the ECU and IAC replacement. If this took care of your code, the car runs good and does not eat oil, you are in good shape. Replacing the spark plugs was probably overdue anyways. If I was you I would pull the spark plugs after 500 and then 1000 and make sure they are not fouled again. Only takes 15 minutes to do and it’s free if you do it yourself… and check your oil frequently.

From what I understand the vehicle was towed in with a dead ECM. The ECM was replaced and fault code P0420 was recorded in the new ECM.

Should they have been able to predict a catalytic converter failure and cylinder wall damage before replacing the computer?

How long was the check engine light on before the vehicle died and need to be towed?

As I understand the mechanics notes, the cat converter fault code was showing before and after the new ECM was installed? If so, how could they send us off with the car, supposedly repaired, knowing that the cat converter had failed? They indicated that they were thought that the converter most likely got sucked into the engine, but I didn’t know that that meant major engine problems. Wouldn’t you expect them to at least do a compression check, since they replaced the spark plugs?