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Discussion Starter · #1 ·
Has anyone ever experienced (and hopefully resolved?) or noticed a 'yellow tinge' on their rear bumper/trunk? I have been battling this since i got the car used in Oct 2019. I believe its from the exhaust but I'm not sure. I have seen similar posts about the issue i've been experiencing, but they are rare to find, and its just a couple people saying 'yeah me too'.

Basically, the entirety of the rear bumper and trunk turn yellow (even the top of the trunk lid), even with weekly/biweekly washes. The only conclusion I've come to so far is that its from the exhaust, as it does not wrap around to the panel gaps. It takes vigorous claybaring to get it off, but it will come off dang near entirely, its just very intensive and right now I'm claying it abput every 1½ or 2 months. I also coat it with jescar powerlock every 4-6 months.

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In the picture, I had already done the trunk (my license plate is yellow too, looks like it sat in a small room with a heavy smoker), but it was just as yellow as the bumper. The bumper came out looking fine after I clayed it too.

It looks significantly worse in person... like really bad. I feel like it sticks out worse than a master blaster fart can.

I'm going to be putting on some GTechniq CSL soon and I'm hoping that will help it come off easier.
 

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2018 Accord Sport 2.0T 6MT
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Sorry to hear/see that, gotta be frustrating! Did you remove or bypass your cat? If not, have you tried using a different fuel brand/source? Can you tell if your car is running too rich?
Running rich should leave a black residue if anything. The yellow is what throws me off. Old clear coat will sometimes look yellow on a white car but the fact that it can be removed and it comes back. I see why exhaust comes to mind but I can't see it turning yellow from that. weird...
 

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It would be interesting to see a Gen X Accord in a wind tunnel as I've noticed that area of my bumper collects dust/dirt/debris after driving. My thought is this is a dead space area and the reason for this occurring and is more visible on a white car.
 

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2018 Accord Sport 2.0T 6MT
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It would be interesting to see a Gen X Accord in a wind tunnel as I've noticed that area of my bumper collects dust/dirt/debris after driving. My thought is this is a dead space area and the reason for this occurring and is more visible on a white car.
It is the only place on my car that has already gathered dust/dirt after a couple days of driving post full wash and wax. It's really odd
 

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The yellowing looks like some sort of heat damage, as if a heat gun was used to dry the bumper. BTW, I only see the yellowing in the middle section of the bumper between the backup sensors.

Another possibility is that someone used a car wash, polish or treatment that leaves a residue on the paint/clear coat. Over time, the sun causes the coating to yellow.

It's also possible that the bumper has been replaced and/or repainted with a poorer quality than the OEM paint.
 

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Discussion Starter · #8 ·
Sorry to hear/see that, gotta be frustrating! Did you remove or bypass your cat? If not, have you tried using a different fuel brand/source? Can you tell if your car is running too rich?
The stock cats are still on. I havent done any mods to the vehicle.

As far as fuel, religiously filled with shell 93 octane. Ive considered trying a different fuel but havent yet.

I appreciate the input!
 

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Discussion Starter · #9 ·
It would be interesting to see a Gen X Accord in a wind tunnel as I've noticed that area of my bumper collects dust/dirt/debris after driving. My thought is this is a dead space area and the reason for this occurring and is more visible on a white car.
Dead space is my thought as well. Unfortunately ive played that game too many times and dont want to play it with my car lol
 

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Discussion Starter · #10 ·
The yellowing looks like some sort of heat damage, as if a heat gun was used to dry the bumper. BTW, I only see the yellowing in the middle section of the bumper between the backup sensors.

Another possibility is that someone used a car wash, polish or treatment that leaves a residue on the paint/clear coat. Over time, the sun causes the coating to yellow.

It's also possible that the bumper has been replaced and/or repainted with a poorer quality than the OEM paint.
Yeah i had already clayed the metal trunk lid where the plate is and a little bit of the plastic bumper when I took the pic.

Im stumped as to what could be causing this. Initially I thought as well it was replaced or something along those lines, but the body lines all match and are even, and i dont think the yellowing would come off if it was from some old residue but I could be wrong.

Also, it seems to find the 'valleys' or low spots in the orange peel and accumulate there first, which is whats pushed me to think it has something to do with the exhaust.

I appreciate your thoughts!!
 

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Discussion Starter · #11 ·
Running rich should leave a black residue if anything. The yellow is what throws me off. Old clear coat will sometimes look yellow on a white car but the fact that it can be removed and it comes back. I see why exhaust comes to mind but I can't see it turning yellow from that. weird...
The fact it comes back so quickly and profoundly is what really has me stumped. I initially thought maybe its pollen, but ive been able to rule that one out.
 

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Does that part of the car get more exposed to sun or do you park it somewhere where automatic sprinklers hit the rear or maybe you're driving through something on a regular basis?

Would it be possible to tell if the clear coat wasn't applied evenly back there? I don't know if UV damage would clay bar off.

Also, is it my bad eyes or an illusion that it looks like there are two column like areas on the rear bumper cover directly under the two inner parking sensors where it's less yellow - like the yellow was flowing down and got redirected by the sensors?
 

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No uv or heat damage would not clay off like that. Polish or compound yes, clay no. Leads me to believe the culprit is som coming out of the exhaust, or something in the system. Maybe the car sat too long. Try maybe a BG valve, fuel system cleaner treatment.
 

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Can we get more detailed pics? Looks like some type of liquid cascaded from top to bottom as i can see the streaks on the bumper. Maybe compound would help, but you're gonna be burning thru your clear coat. You did mention that it's used. Did you notice the discoloration on the bumper before purchasing?
 

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Discussion Starter · #16 ·
Does that part of the car get more exposed to sun or do you park it somewhere where automatic sprinklers hit the rear or maybe you're driving through something on a regular basis?

Would it be possible to tell if the clear coat wasn't applied evenly back there? I don't know if UV damage would clay bar off.

Also, is it my bad eyes or an illusion that it looks like there are two column like areas on the rear bumper cover directly under the two inner parking sensors where it's less yellow - like the yellow was flowing down and got redirected by the sensors?
Yes exactly on the two columns! It looks like it drips around the sensors!

As far as sprinklers/driving through stuff goes, im sure its not that because it had this stuff on the bumper when i bought it. I bought it in the evening so the lighting wasnt the best and i didnt notice it, but it was yellow when i got the car.
 

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Discussion Starter · #17 ·
No uv or heat damage would not clay off like that. Polish or compound yes, clay no. Leads me to believe the culprit is som coming out of the exhaust, or something in the system. Maybe the car sat too long. Try maybe a BG valve, fuel system cleaner treatment.
Can it sitting too long cause this? The car is used and had this when i bought it, but didnt see the yellowing when i bought it because it was night, but it was already yellowed.

I would believe it sat a while before i bought it because it was dirty and the way the dirt sat on the paint and how dirty it was, i initially did think that it sat for a while when i first got the car.

Also, it looks like the yellowing clumps up in the valleys/low spots of the orange peel before it totally films over the clear coat.
 

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Discussion Starter · #18 ·
Can we get more detailed pics? Looks like some type of liquid cascaded from top to bottom as i can see the streaks on the bumper. Maybe compound would help, but you're gonna be burning thru your clear coat. You did mention that it's used. Did you notice the discoloration on the bumper before purchasing?
Yeah it had the yellowing when i bought it but i didnt notice until the next day because i got the car at night.

I will get some better pics but unfortunately im going to have to wait for it to reaccumulate because i finished off the car after i took this pic.
 

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Since you're not the original owner the next time this discoloring comes back you may want to seek professional (paint/auto body repair) help. With it keep coming back it may be the result of a repair/paint job that either wasn't done right or wasn't taken care of after the repair (not letting the paint cure/etc.) that is causing this issue.
 
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