When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Rough idling after filling up on gas,PO433 Code after replacing EVAP Purge Valve
Hey everyone! After replacing the EVAP Purge Valve, in an attempt to fix a EVAP system problem, my 350Z is now throwing a P0433 code—something that wasn’t happening with the old purge valve. It also ran rough immediately after filling up with gas, but smoothed out after a few miles of driving. (Currently, it idles fine.) I recorded a video showing how it was idling roughly after that fill-up + the installation of the purge valve. Before diving into the specifics, here’s some quick info on the car:
The chassis has ~242,000 miles, but the previous owner said the engine was replaced. The CarFax report backs this up, and the seller claimed the replacement engine had ~100,000 miles on it. Whether that part is true is uncertain.
I’ve been chasing a common issue with these 350Zs - EVAP system problems causing the gas pump to “kick back” due to excess fuel vapor. Oddly, I’ve never had an actual EVAP code until now. I’ve replaced a ton of parts on the car, including several fuel and EVAP components, to address this issue. Below is a list of everything done to the fuel and EVAP systems (I can list other unrelated repairs if needed):
Entire charcoal canister, gas cap, and a few associated hoses w/ the charcoal canister (9/14/24)
EVAP purge solenoid (4/18/25)
The first video shows how it was idling (or, lack thereof) after filling it up with gas today. The second video shows how I installed the purge solenoid/where the two lines connected to it go. I have also attached a large document with all the research I have done and some notes I made along the way (maybe it'll help somebody else who is having a similar issue.)
Any help is appreciated!
When you fill up the tank, are you force feeding it gas? This can cause the charcoal cannister to get flooded and clog.
Note: There's a TSB for the gas fill issue, Nissan crafted a bracket that needs to be purchased and installed inside the fuel tank to resolve this issue. I have an 06 Enthusiast that had this problem Ever since I installed the bracket, it solved the problem with fill ups. It's not a fun job to complete, but worth it in the long run.
P0433 is related to your bank 2 catalyst. This might be purely coincidence as the EVAP system should not impact your catalysts.
What injectors did you use? Where did you source them?
Same question for the purge solenoid?
First, thank you for taking the time out of your day to reply. I appreciate it.
1.By force feeding, do you mean pumping gas even though the car is already full on gas? If so, I have never done this since I know its unhealthy and, as you said, can clog the charcoal canister. The TSB you mentioned- could you possibly send me it?
2. I have also been experiencing a P2A03 code for the sensor 1, bank 2 O2 sensor (my post about it here) which I presume is what you are referencing when you say that the PO433 code is related to- but most sources say that the PO433 is because of the purge valve. I'm not saying you aren't wrong, I'm just a little confused on this. Here is a link showing all the codes my scanner recieved as of yesterday, after filling up on gas and experiencing rough idling.
3. I didn't purchase new injectors, I simply replaced their O rings since I had easy access to them while doing valve covers and other stuff. I bought the O-Rings from Z1.
4. The purge solenoid I sourced from RockAuto. It is the exact same one as seen on Z1- I didn't go with a no name chinese brand or anything like that.
The code you wrote in original post is for P0433 (Cat efficiency), but the code you actually have in the screencap of your scanner app is P0443 (evap code). Two completely different codes/faults, hence the confusion.
If you have an active P2A03 (Upstream O2 sensor code) that will for sure cause rough running conditions. Sounds like you need a new O2 sensor or you have a bad/flakey harness connection if the issue is intermittent.
I'll see if I can dig up the "hard to fill tank" TSB.
-Icer
Reading your other post. I would replace all aftermarket sensors (O2 & MAF) with OEM. I also recommend switching back to the OEM throttle body and intake just to rule those out as possible causes. With the number of mods you've done, you really should get a proper tune done (Uprev or something similar).
My bad with the code mix up — you’re totally right, the PO433 code is EVAP related, not O2.
Regarding the rough running: it’s only ever happened after installing the new purge valve, and only immediately after filling up the tank. My O2 sensor issues (P2A03) have never caused this type of behavior before and they've been problems since I bought the car. Maybe the new purge valve (which is, probably working right) is making the engine run differently, thus giving different signals to the O2 sensor that in conjunction cause problems?
Once finals are over, I plan to swap the old purge valve back in and see if the code goes away.
Going full OEM on all of the O2 sensors is out of budget right now. I’m going to replace the sensor's harness first and seeing if that improves anything. (The MAF sensor is OEM, by the way.)
I agree with you on the mods—it’s possible one is contributing to the issue. Once I take care of a more critical problem (my convertible top has its own set of gremlins,) I plan to get some flavor of tune but I haven't done enough research to decide which one yet.
The PCV Kit I installed was this one from Z1 (this one).
(Probably wrong) theory I thought of:
If the EVAP system has a blocked line somewhere—preventing vapor from being properly routed—then when I fill up the tank, the displaced fuel vapors might be getting forced through the purge valve, causing the car to run overly rich and stumble.
If the old purge valve was stuck closed or non-functional, those vapors wouldn’t be getting pulled in, which could explain why there were no issues before. That’s just a theory though—I’d love to hear your take on whether that even sounds plausible or if I’m way off base.
Lastly, if I am able to scrounge up some spare time this weekend, I plan to make a trip to my local Pick n' Pull as they have 3 (3!!) ZRs in stock. I'll probably buy the O2 harness, purge valve (they do have an 06' it appears,) and a few other small things. What I choose to buy depends on how fair the prices are, my username choice is very deliberate lol.
Your theory has some merit. A simple test is to try blowing through the valve, if air passes through easily, then it's stuck open (bad). If air cannot pass through, then it's closed (good). You can also try using a 12V battery with some alligator clips to test it's functioning properly. I'm pretty sure those are a simple 2-wire harness (Batt +12V & Ground).
If you hit up the local Pick-N-Pull, be mindful about the O2 sensors. I believe the 03s have different harness plugs vs. later years.
Other items you might consider while you're there.
1) OEM Cam Sensors.
2) OEM Crank Sensor.
3) OEM MAF.
4) OEM throttle body.
5) OEM VTC solenoids.
6) OEM Coil packs.
7) OEM Fuel Pump.
8) Keep an eye out for aftermarket goodies.
I recently came across a 350Z in a Pick-N-Pull with DC Sport Headers (ceramic coated), and Plenum spacer kit. It also had some no-name brand adjustable rear control arms. If I had more time, I would have gone for the DC Headers as they're worth a pretty penny and also CARB legal. But I ended up walking away with the entire intake plenum & spacer for only $50. I plan to use it as a learning/training project with porting. It's the correct plenum used by Motordyne for the MREV2 (which no longer seems to be available). I was really hoping the previous owner had the MREV2 installed on the Z, but sadly no, just a spacer.
All budget permitting of course. Also if any of these items listed aren't OEM, I wouldn't bother with them. Also note, the 06 ZR with the 6MT has the Revup DE, meaning some sensors & harness plugs "might" be different (double check the CAM sensors/plugs & O2 sensors/plugs). Take a photo of yours before heading out to ensure you're not wasting time & money.
Cheers!
-Icer
Regarding the Z1 Silicone PCV hoses. Simply put, I don't trust them. After getting some mileage on them, check and see if they're sweating oil or have an oily layer on them. PCV hoses specifically need to withstand a healthy vacuum without collapsing. If the Z1 silicone hoses are not reinforced properly, they will collapse. I tried silicone PCV hoses before from Mishimoto and they were trash, they had both issues I just mentioned. I know, not the same brand, but I bet they use the same supplier/manufacturer. My recommendation is stick with the OEM hoses when it comes to the PCV and Coolant plumbing. But hey, I could be wrong and maybe Z1 has an improved design.
Cheers!
-Icer
Something interesting happened today. I’ve been awfully busy (and a little under the weather), so I ended up letting the fuel level drop to about 30 miles 'til empty, or around halfway through the last quarter of the tank. This is the lowest I’ve ever let it go; normally, I fill up before it dips below a quarter, since I know letting it run nearly empty isn't optimal.
When I filled it up today, I had zero issues with the gas pump clicking off from vapor pressure. The entire time, it filled up smoothly, stopping right before 16 gallons. Still had the rough idle afterwards though.
Once I get around to pulling the purge valve, I’ll definitely test it for whether it’s stuck open or not, just like you suggested. And yeah, you're absolutely right, the O2 sensors and the purge valve vary depending on the year. Sadly, the only 2006 at my local Pick-n-Pull was inventoried way back in January and already looks wrecked and pretty stripped in the photo, so I’m not holding out much hope for usable parts there.
As for the parts list: I’ve already replaced the cam and crank sensors w/OEM, so those are covered. My MAF and fuel pumps are also OEM (fuel pump came out of a low-mileage donor). I replaced all 6 ignition coils a little bit ago since one of them was wasted (probably from the previously leaking valve covers) and causing rough running. I went with the "high energy" ones Z1 puts their name on, and it woke the car right up. So far I'm happy with them (but damn are they expensive!.) I’ll definitely keep an eye out for a VTC solenoid (seeing how expensive a new one is), and I’d love to find a plenum spacer, although I’m definitely holding off on installing anything new until I sort this whole EVAP situation out.
On the Z1 PCV hoses, I installed them back in December at around 239k miles, and I’m sitting at 243k now, so they’re still fairly fresh. I’d be surprised if they’re already failing, but I’ll check for signs of collapse or oil sweating once I’m back from Pick-n-Pull.
Once again, appreciate the advice!
Last edited by MoneyPitZ; May 9, 2025 at 04:32 PM.
Two days before today, the 2006 disappeared from their inventory. It seems like they crushed whatever rest of it was left, therefore I was unable to grab compatible the O2 sensor harness and purge valve. D'oh!
A third Z they claimed to have also didn't exist (either that or they moved it out of the row the website said it as in.) D'oh x2! However, there were still two: the most recent one, a blue coupe, inventoried only a month ago and a convertible. They were both pretty stripped but still had usable interior pieces and trim that I wanted. (There was also a cool 80s volvo wagon and a first-gen integra at the yard, but I forgot to take a picture of them.)
Lastly, my trunklid came in. My z's color is "L40 Interlagos Fire," which is a rare (yet beautiful) color. The trunk lid and tonneau cover have really bad clearcoat failure, and for many reasons, it doesn't make sense to get them repainted. So I bought a trunklid with good paint (only a few spots of easily repairable clearcoat failure,) had it shipped, and my tonneau cover will be here sometime this summer.
- Instrument Cluster (mine's got paint problems) - Early style A/C ***** and controller box - Door vent and interior door handle - Door card a-pillar triangle (it seems they always break: two of mine are broken, and I was able to harvest one usable one from the junkyard.) - Weatherstripping (not seen here: convertible door weatherstripping costs an exorbitant amount, I paid 5 dollars for mine.)
Old trunk lid Sooo much better. Now just gotta tackle the tonneau cover. Here is your prize for helping me along my journey: a beautiful photo of my car.
Anyways, now that I have added 200 gb of photos to the My350z.com data server, I'll be heading out for now.
Last edited by MoneyPitZ; May 11, 2025 at 04:39 PM.
At last... the service engine soon bulb gets to rest. The solution has been found! Plus a pleasant surprise.
Let me recap the discussion here. For the solution, just go to the last bolded line.
Since I got the car in 2023, I've had problems with the gas pump being kick backed (common problem on these cars) even if the tank wasn't full. I also had a SES for an O2 sensor, which at the time I thought was unrelated. (More on this later.) I didn't have any codes for the EVAP though so I was kinda just blindly fixing things and hoping for the best. So I did the usual steps for fixing EVAP system problems, including replacing the gas cap, charcoal canister, and the little solenoid inside the canister: unfortunately, none of these fixed the issue. At this point, I decided to go ahead and try replacing the purge valve solenoid.
So, I go to RockAuto to buy my purge valve solenoid. This is where I made a critical error.
However, I didn't know that at the time. I install the new purge valve, drive around for a little, and uh oh: now I have two different codes. Searching up the new code, "P0443" (I erroneously put P0433 in the title, oops,) I learn that it is caused by a faulty purge valve. This is strange, I thought at the time, since I just put a brand new purge valve in. (Because surely brand new parts never fail!) The car also ran poorly after filling up the gas tank with the new one in. After this, I made my original post a few months back, and for more details regarding my thought process you can read through the replies above.
Honestly, I would have probably lived with the problem but where I live, a SES light = failed emissions. And guess who's car needed to be inspected? So with no choice, I bring my car in to the real mechanic and today I just got diagnosis as to what was happening.
The old, original purge valve solenoid was barely working. It wouldn't release the correct amount of gas vapors. (For some reason this one never gave me a code though.)
My RockAuto cheap@ss special managed to short itself out. It was fully open and letting in way too much gas vapor, causing the car to run poorly after filling up with gas. So, don't buy a purge valve from RockAuto. This has to be the 5th brand new part in the past two years that has ended up biting me in the rear. Way too many new parts are crap, especially the cheap ones... let my mistake be a warning. All of this headache and I didn't even save money by going cheap.
The solution? A brand new OEM purge valve solenoid. That's it. P0443 is no more and the correct amount of gas vapor is being released.
(Update: Now that the purge valve is fixed, the code is back up, probably due to another EVAP system issue. I trust my mechanic so I don't have doubts that the new purge valve he installed is working correctly.)
The new OEM purge valve also appears to have gotten rid of the P2A03 O2 sensor code I had, since that code no longer shows up and my car passed emissions perfectly. (I'll update this portion in a few days too since it could reappear.)
Lesson learned: Choose your non-OEM parts carefully. Or just go OEM.
Last edited by MoneyPitZ; Aug 26, 2025 at 02:55 PM.
Thanks for the follow-up Money. This is why I'm a big believer in just paying the higher prices and going with OEM when it comes to sensors/electronics. There are some good aftermarket parts out there, but the global market supply has been flooded with cheap counterfeits posing as quality OEM and even some name brand aftermarket. I've also heard recently that RockAuto has allegedly been selling some counterfeits (intentionally or not). If you don't have knowledgeable people in charge of bulk ordering and managing the supply chain, then it's very easy to get scammed. I think RockAuto works on a partner supplier network of warehouses all around the U.S.. Similar to how Amazon handles partner sellers. This means the vetting process for many parts sellers could be flawed. I bet there's limited inspections or quality control measures since doing so would be very costly.
Even some of the higher quality aftermarket companies have started selling garbage. Reasons are varied, but generally I think it's been from changes to manufacturing locations (one country to another) in an effort to improve margins. Other times its simply changing to lower quality/cheaper materials (design changes/compromises).
Not only should you choose your parts carefully, but be very careful about who/where you buy them from! Avoid Ebay & Amazon unless you know how to spot counterfeits. I would even go so far as to say avoid RockAuto when it comes to electronics and ignition system components (spark plugs, coil packs, injectors). I still use Rockauto for basic items, but I've been burned more than once even on simple stuff like radiator hoses and thermostats. For this reason, I typically just purchase OEM these days or try to rebuild OEM components when I can (like PS pumps and Alternators).
Cheers!
-Icer
After fixing the problem with the purge valve located close to the engine, P0443 is back. This time I think it's the "Purge Volume Control Valve," yet another purge valve located near (or in, I forgot) the charcoal canister. That was one I also replaced with a RockAuto part and I wouldn't be surprised if it is also bad, throwing the same code. I'll replace it with an OEM one... eventually, and I'll post (again) if that finally gets rid of the stupid code. I'm not even annoyed, just amused at this point.
At least the O2 sensor one is gone, for now.
Last edited by MoneyPitZ; Aug 26, 2025 at 01:48 PM.
Small update: Decided to replace the EVAP canister purge valve w/ an OEM unit since that was one I had also replaced previously with a RockAuto unit. The OEM one was a lot more sophisticated looking, and I was hopeful that this would finally clear P0443. Unfortunately after only a few miles of driving, next morning the light was back on (as well as P2A03.)
TLDR: After replacing my cam and crank sensors, my car no longer runs horribly after refueling. Idle still isn't perfect but it clears up after a few minutes, and I still have a CEL for P0443.
(Story Time/Yap)
Last month, my car started running poorly after sitting in heavy traffic. The exhaust was producing very loud "pops and bangs" like it was on a burble tune, smelled rich, and wasn't idling well unless I was actively giving it throttle. My scan tool indicated that it had timing that was jumping from 13-19 degrees randomly as well.
At first, I thought I had already replaced the cam sensors, but checking my maintenance logs revealed that I had actually replaced the knock sensors, not the cam sensors. (I had previously stated that I replaced the cam sensors earlier in this chain too, which I now know wasn't true. My bad!) After some research, the symptoms I had pointed towards failing cam and crank sensors.
I ordered and installed Hitachi cam and crank sensors, and boom, problem solved. Not only was the problem solved, but the car is now getting better gas mileage, the engine is quieter, and power delivery is much smoother. I believe that the cam and crank sensors had actually been bad for a while, but ultimately completely failed after sitting in traffic. Unexpectedly, refueling now no longer results in wild rpm fluctuations, though it does idle a tid bit funny for the first few minutes, ultimately clearing up. Still battling P0443 but it hurts less to refuel now.
Rough idling after filling up on gas,PO433 Code after replacing EVAP Purge Valve
