The software programmer had to satisfy EPA standards in place at the time the vehicle was manufactured. Those standards are much more stringent than the testing now being done. Just because the vehicle passes the NOx test 12 years down the road, it doesn't mean the system is working as it was designed to, so if the computer decides it's faulty, it's faulty.
If you can't figure out how to fix it, well, that's another issue.
Ah yes, that's what the knock sensor deals with. Which his engine has assuming he's got the 3.0 at least.
If his NoX production is low the engine isn't going to detonate since NoX production is directly related to cylinder temps. That is why I told him to have it emissions tested.
I first attempted to order the TRANSDUCER separately since the EGR valve itself passed the vacuum test that the service manual recommends trying. The transducer and valve are NOT sold separately, not from the dealer nor from any aftermarket source I ever tried calling, at least not for my vehicle. More FUD from you I think. And totally unnecessary since as I already said the dealer is cheaper than aftermarket for this part - and you could also have verified that for yourself in 5 minutes of phone calling.
The EGR valve itself is simple and if it will pass a vacuum leakdown test and if it will cause the engine to stumble when vacuum is applied, it's working.
The transducer contains 2 parts and it is designed to be taken apart. The first part is the selonoid which is sealed. The second part is the diaphram which is in a housing that can be taken apart. One side of the diaphram is exposed to exhaust gassses. I've long experience with EGR and I know from experience that the parts that touch the exhaust gas stream are generally the first to go.
When I first bought my 95 and it failed emissions I took the transducer apart and found the diaphram was cracked, obviously long exposure to exhaust gasses ruined it. That is why I tried to get the transducer separately.
The selonoid can easily be tested by applying vacuum with a hand pump and actuating the selonoid with 12 volts.
While it is conceivable that the selonoid could bind under a temperature change - for example if underhood temps were hot - thus setting the CEL - I've seen the same behavior with the CEL with several transducers, new, used, and used known good. I've tried multiple egr valves as I've said without a difference. I've tried multiple ambient air temps as well. I've tested it multiple times under the state IMS program. Oregon allows you to test for free if your not renewing registration If NoX is low, then the engine is not detonating.
Anyway, back to the OP's vehicle. I never advocate shotgunning without testing. Quite obviously the right way to do it is for the OP to start by following the EGR valve tests in the FSM. Obviously if his transducer's selonoid is stuck or the EGR valve is leaking, then he needs to replace the valve. But, a emissions test would show these as well since those would give high NoX.
But, the OP didn't indicate that he wanted to do anything OTHER than shotgunning. That is why I told him to have it tested for emissions. If he passes NoX then EGR is working no matter what CEL says.
Ted
The most common reason why the EGR valve solenoid fails is water getting into the solenoid and shorting out or gets to the connector will corrodes the terminals to the point they break off or just don't make contact
No knock sensor on the 2.5 or the 3.0
NOx production could be masked by the catalytic convertor.
Partially plugged EGR passages would still yield the engine stumble when the EGR is opened yet allow that the EGR monitor fail.
True enough. Left to go long enough, the solenoid also suffers.
The exhaust back pressure was? The MAP signal responded how when the EGR was commanded? The O2 signal responded how when the EGR was commanded?
Easily handled by the Cat-Con if it's anywhere near original efficiency.
The EGR backpressure transducer in my 3.9 Dakota leaks like a sieve when tested with my smoke machine, the truck passes the state IM-240 as a fast pass.
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