Check Engine Code P0456: Tag Expires in 22 Days

Maintenance/Repairs
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83

THE SAGA CONTINUES

So, where last we left off, after completing the repair; and then completing the repair that was needed after the repair; the monitors were all ready except for one.

However, when driving it around some more, for some reason the battery cable came loose and all the monitors needed to be reset. So that was Wednesday.

By today, Monday, there were three monitors still not ready (the person who was driving it told me his boss wouldn’t let him drive it very much each day). This was exceedingly frustrating.

So I took the car and drove it around myself to try and get the monitors ready. But then, after driving it like 10 miles, the check engine light came on!

Turns out it was a P420 code: low catalyst system efficiency. So that had nothing to do with the evap problem that I initially went there for. Still, it’s strange that all these things are going wrong after they replaced that part to fix the evap problem.

The catalytic converter was replaced a few years ago, and only has 15,000 miles on it. So it seems strange that it would go out.

I asked the mechanic if this could have anything to do with the electrical system, and he said no; that the catalytic converter isn’t electrical. Still, the sensors that feed into the computer are electrical. So it’s just very strange that all these issues are happening right after they replaced that part.

In any case, the mechanic cleared the code, and I added some RXP to the tank, in hopes that that will help the situation. And I’m just driving it around myself to try and get the sensors ready. Hopefully they’ll be ready without the check engine light coming back on.

I know that Texas, where I live, has a low mileage waiver if you drive less than 5000 miles in a year and have an emissions related issue. I wonder if P420 would qualify for that. Seems that it should, right?

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Have you ever watched the film where two trains are approaching each other on same track, they are a mile away, yet no way to prevent what’s about to happen? That’s what I’ve been seeing while monitoring this thread.

Don’t know about TX waivers, but p0420 (p codes are always 4 digits) means the drivetrain computer isn’t seeing the expected relationship between the signals for the pre-cat O2 sensor and the post-cat sensor. Likely possibilities

  • faulty cat
  • one or both of the o2 sensors faulty
  • wiring from o2 sensors to drivetrain computer faulty

My guess, something about the way the engine computer has been working with the evap-fault-mode present and the various driving that’s been done to enable the monitors, all that has unfortunately damaged the cat. Running engine w/too rich or too lean operation can damage a cat. Before replacing cat makes sense to check all possibilities of course, especially a visual comparison of the signals from the two sensors. Sophisticated scan tools (i.e. the expensive ones) usually have that function built into the software.

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Indeed! I paid them for the work they did and hopefully will never have to go back to that place again!!

A few points I left out of my previous post.

I normally fill up with E15 gasoline (my car is flex fuel). Today, the tank was 1/4 full, so I put another half a tank in. But the station didn’t have E15, so I added regular unleaded (87%). I don’t know if that’s a factor.

Also, I keep a bunch of loyalty cards in my glove box. When I picked up my car today, the glove box was open, and some of the loyalty cards were on the floor. At first I thought someone might have gone through my glove box when the car was parked. But nothing was missing that I could tell.

Then it hit me: on Wednesday I was told that the battery cable came loose, which caused the monitors to reset. How hard do you have land from a bump to cause a battery cable to come off the post?? Pretty hard!

So my theory (which I believe is correct) is that the guy was driving really, really fast with my car; didn’t slow down for a bump, went flying in the air and landed hard – hard enough to cause my glove box to fly open and some of the loyalty cards to come flying out. And, possibly hard enough to damage the catalytic converter or O2 sensors. That’s what I believe may have happened.

1 Like
86

Also, I just drove it around and noticed that my cruise control isn’t working anymore! When I drove it earlier I noticed it worked at 35 MPH, but didn’t work at 55 MPH. Now it doesn’t work at all. So I don’t know what’s going on with that. Just seems a lot of things that were working previously aren’t working anymore.

Oh, and while I was idling I noticed sort of a “scraping” sound coming from the engine. Like there was the regular engine sound, which sounded normal, and then there was also a sound that sounded like metal scraping on metal.

I made a video of it, but it’s hard to hear the scraping sound over the regular engine sound. Was easier to hear in person. Anyway, here’s the video.

87

Probably either nothing of import, always been there you just hadn’t noticed. Or a belt is out of alignment. Check areas were belts are close to plastic parts , like engine shields, wheel-well shields, etc. I had something similar on my truck, cooling system hoses removed for inspection, reinstalled, caused minor interference with the very tip of the fan blade, buzzing noise. Years ago after some seriously difficult & time consuming VW Rabbit diagnosis & repair to fuel system, started to notice very high pitch whining noise, almost imperceptible, coming from engine compartment, louder & even higher pitched when accelerating or going fast. Thought there was some major problem. Turned out that noise is normal, always was there, normal sound of the fuel injectors … lol

Whether car was improperly driven, that’s pretty much speculation. Good chance battery cable came loose b/c it wasn’t tightened securely in first place. And glove compartment contents strewn about b/c glove compartment had to be emptied for some reason. I have to remove glove compartment in my truck to access hvac systems. In Corolla, I generally remove glove compartment as part of the process of disabling fuel pump.

Has your car passed the emissions test?

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No, the glove compartment wasn’t emptied. Almost all the items were still in the glove compartment. But some of the loyalty cards were on the floor, which would have happened it someone landed hard from a bump and some of them went flying out.

Also, I asked the mechanic about it, and he said he didn’t know. Said they don’t go into that. And he would have been the one to have removed it.

Besides, even a loose battery cable will stay on the post unless there’s a big jolt to make it come off.

I seriously believe that that’s what happened, and might have caused the damage to the cat and the cruise control (cruise control is manual, where a mechanism physically pulls the accelerator down; so very likely something in that mechanism got damaged).

Funny you should ask! I was driving around today, trying to get the monitors ready (the mechanic cleared the P0420 code, so I had to start over with getting the monitors ready). I hit 80 miles and the check engine light came back on. :frowning:

So I called the Texas DPS and discussed my situation with them. Since I drive under 5000 miles a year and have spent over $100 on repairs, I qualify for a low mileage emissions waiver, even with the P0420 code. I just have to get two failed inspections and then bring it into the DPS office for a physical inspection.

So tomorrow I go back to the place to get two failed inspections (back to back). Hopefully the monitors will be ready.

Do you know, by chance: if I currently have a check engine light, will that interfere with any of the other monitors not becoming ready if they’re not yet ready, but I drive it around some more? Thanks!

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Beyond my pay grade. But maybe some of the OBD II experts here know.

90

A loose battery cable terminal clamp will usually break connection when cranking the engine, the high amperage load of the starter motor requires a tight connection. I think the stunt driving scenario is unlikely.

91

Good to know! I hope that’s the case. I hate to think the person was reckless with my car (perhaps not intentionally, but perhaps was in a hurry and going fast and not paying attention).

But, while I hope that’s the case, that still doesn’t explain how the glove box popped open and a few of the cards were on the floor. Sure, someone might’ve rifled through it at some point (though I don’t know why some of the cards would have ended up on the floor). But that seems to indicate a hard landing causing it to pop open, though maybe not.

And then there’s my mechanical cruise control which was working and now isn’t working. Again, purely speculative. But a strange coincidence that that happened at the same time that the cat started having problems and the glove box popped open. But all three could be explained by a hard landing at speed.

And last, the battery cable was removed when the repair was done and then replaced. After that, the person drove it around for a while to get the monitors ready. He got all but one monitor ready. So the cable stayed on through at least one engine start, probably multiple.

Like I said, all of this is purely speculative. But there’s so much unexplained re. the cruise control, the cat converter, and the glove box issues, all happening at the same time, that the landing at speed scenario seems at least a possibility.

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THE LATEST

Got two failed inspections today, which are a requirement to get my low mileage emissions waiver. Just need to get an appointment with the DPS inspector and take my car there. Then, once they sign off on it, I’ll be able to register the vehicle!

However, the office near my house only inspects on Wednesdays, which is today, and I don’t know how long it’ll take to get an appointment. Am checking with a different office to see if they can squeeze me in.

Meanwhile, two days left on my tag. Texas has a five day grace period. So it’ll be down to the wire.

That’s all on the registration front.

On the repair front, as noted there’s a P0420 code that remains, which I’ll just have to deal with at some point. But the waiver is good for a year, so no rush.

However, when the guy did the inspection today, the car threw a P0456 code, which was the original code I had the repair done for. So it should not be doing that.

So I left the car with the shop and they’re going to have the mechanic take a look at it and see what’s going on.

Found out the answer: no, the check engine light doesn’t prevent the other monitors from being ready. I continued to drive it around, and they eventually all became ready (at 92 miles).

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Homeless people looking for money. Do you trust the person that drove your vehicle for parts and lunch to lock your vehicle at each stop?

Did they tell you this? There is no need to disconnect the battery when replacing a purge valve. Some people avoid disconnecting the battery for fear it will cause calibration problems.

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No, I don’t think they locked the car at each stop; only at night. So, yeah, I suppose it could have been a homeless person. That’s possible. That would just leave the mystery of how the cruise control went out and the cat started throwing a code all at the same time. But maybe just a coincidence. Like I said, this is all just speculation.

No, not when replacing the purge valve. After they replaced the purge valve they took it out to drive it and the car died. Turns out there was a broken wire in the wiring harness, and they disconnected the battery when replacing the wire.

I don’t know if the mechanic accidentally broke the wire when he replaced the purge valve, or if it’s just another coincidence. Either way, they didn’t charge me for replacing the wire, which was great. So I think they suspect that at least they might’ve caused it.

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P0456

Evap system works correctly only if air-tight. Evap system is mainly for reducing HC air pollutants; generally a p0456 problem wouldn’t adversely affect the engine operation or performance. The way the test works, I believe on Chrysler products (such as your Dodge) the computer closes all the valves to isolate the system, then commands a pump to pressurize the evap system with air. Next it monitors the pressure inside the system, measurirng how long it take to deflate. Sort of like you’d test a balloon’s ability to hold pressure. You can pretty much figure out the most likely failure modes: hose or fitting isn’t sealing, faulty valve (purge or vent usually), faulty air pump, faulty pressure sensor. Note that the test might only be done with the fuel tank between certain levels, so for example if the tank is always driven near empty, or always near full, the test might never initiate.

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Good to know, thanks. It’s sort of puzzling that the readiness monitors could be in the ready state – presuming this means they passed – and at the same time there’s a check engine light. Implies there are reasons for a check engine light that have nothing to do with the emissions system requirements. Wondering what those are?

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Right. But, still, that was what I brought it in there for in the first place, and which they replaced the purge valve for. So it shouldn’t be happening. And if I get the cat problem fixed, then I’ll need the P0456 code to not be there next year in order to pass inspection. So even if it doesn’t affect my engine operation, it’s still something that needs to be addressed.

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There’s other leak spots that could cause an p0456, see my post above. The purge valve might not have been the only leak. Or the new purge valve could be leaking. Shop will have to keep trying. To find these sorts of leaks quickly shops often pump a smoke-like-substance into the system then they watch where the smoke is coming out. Is your shop using that method? Sometimes the leak is at the top of the fuel tank, and fuel tank has to be dropped to get to the bottom of it.

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I don’t think that’s true (that ready = passed). When I first got the P0456 code, it showed “ready” but “fail.” I’m pretty sure that “ready” just means it completed the various tests. Pass/fail is a separate thing, I believe.

100

Ok, so they have to be “ready” and “pass”. “Ready” and “fail”, car still wouldn’t pass emissions test. So are all of yours “ready” and “pass”?

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Right. But it should still be covered under the diagnostic that was done. So, if there’s another leak, then that means they missed something. Or, if the purge valve is faulty, then it needs to be replaced.

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All are “ready” but the minor evap leak and the cat issue are both fails (P0456 and P0420 codes).