Hey everyone,

I’ve got a 2015 Honda Fit that I bought in 2015 with just 3k miles, and it’s now sitting at around 170k. Last month, it started leaking oil pretty badly, and it turns out the timing chain had worn through the timing cover. I found a local guy selling an engine listed as a 2015 on eBay and decided to pay him cash to install it, thinking it’d be quicker than repairing the chain and cover myself.

After picking up the car, I immediately got error codes P0087 (fuel rail/system pressure too low) and P0088 (pressure too high). Upon inspecting further, I discovered he had actually installed an engine from a 2018 Fit, and from my research, I found out that the 2018 uses a different fuel pump. I ordered the correct 2018 fuel pump and installed it, which cleared the P0088 code, but I’m still getting the P0087 after a few minutes of driving.

I’m pretty mechanical and honestly should’ve just replaced the timing cover and chain myself, but I thought a low-mile engine (8k miles) for $1,700 installed would save me time. Now I’m at a loss. I’m thinking the next step might be replacing the fuel pressure sensor on the rail, but I’m having trouble finding the correct part number.

Does anyone have any insight into what might have changed between the 2015 and 2018 engines that could be causing the fuel pressure errors? Any advice on how to proceed would be greatly appreciated!

Thanks in advance!

 

Attached is a video showing the fuel pressure drop at the 1:02 mark. The pressure on my diagnostic tool starts around 9000 kPa, but suddenly drops to 210 kPa and never recovers. If I turn the car off and back on, or disconnect and reconnect the sensor, the pressure goes back to the thousands making me think it is a sensor issue.

 

Update. Still no luck but it appears the computer is cutting off the high-pressure fuel pump as I can audibly hear it click and am getting the same results by disconnecting the hpfp connector when the pressure drops.

 

Update: I removed the fuel pressure sensor from the rail and cleaned it with a Q-tip and ether. After cleaning, the HPFP (High-Pressure Fuel Pump) didn’t shut off for about 50 miles, even with multiple stops and starts. I then ordered a new pressure sensor (part #499000-8450) from Amazon and installed it. I cannot make out the D number underneath and am not sure if this affects anything. However, after installation, I got the following codes: P0088, P0087, P0193, and P2623. I cleared the codes and took the car for a test drive, but within less than a mile, the HPFP shut off again, and the car went into limp mode returning the same 4 codes.

I removed the new sensor, reinstalled the old one, cleared the codes, and am currently testing again. So far, I’ve driven about 15 miles with no codes returning. I should note that I’m keeping the car under 3-4k RPM—if I go over, the HPFP shuts off again, and the car goes back into limp mode.

 

update. After switching back to the old sensor, the car ran fine for the day. The next morning, it popped code P0087 (low fuel rail pressure) again and went into limp mode. I let it warm up and restarted the car, and it ran fine all day—approximately 320 miles of driving as we were running the kids around. However, if I press the gas pedal all the way to the floor, it returns to limp mode and pops code P0087 (low fuel rail pressure).

The variables I am now consistently seeing are:

• P0088 (high fuel rail pressure) from a cold start (think 8+ hours), but it seems to be fine after sitting for 2-3 hours.
• P0087 (low fuel rail pressure) when pushing the car past 4,000 RPMs.

The HPFP is brand new and engine from 2018 only has 8,000 miles and seems to be running fine otherwise. I did not have this issue with the 2015 engine; the only problem with that one was the massive oil leak from the timing cover. My next guesses will be the fuel rail and injectors, but I hate to keep throwing money at this without a logical explanation.

 

Maybe try cleaning the mass airflow sensor? Sometimes that can cause weird fuel issues.

 

Update.

I now have about 4k miles on the new engine with no new issues. However, I'm still getting a low fuel pressure code after extended periods of sitting, and this seems to be happening more frequently as the weather gets colder. For example, yesterday it was around 30 degrees, and after sitting for only 3 hours, the low fuel pressure code popped up again when I started the engine. Normally, this only happens after sitting for 8+ hours, and it can be bypassed by pressing the gas pedal for a few seconds upon startup.

Also I'm still experiencing the low fuel pressure code after a few seconds of fully pressing the accelerator under load.

 

Bobbie, you rock! Hope you get to the notion of this

 

Awesome troubleshooting! We are running into the same problem ourselves. Swapped in a lower mileage engine form a 2019 to a 2017. Differences with fuel pump, fuel pump housing, fuel piping caused us the same problems and codes p0087 and p0088. Now we are getting the fuel injector circuit code. Also to note, the hpfp is making a chirping noise that was never present in the old engine. Car still randomly goes into limp mode and sometimes doesn't start. We haven't tried switching sensors yet as you did. We were thinking it may have something to do with the Ecu reading it wrong. The part number on the newer model ecu is different than ours. As well as the engine harness. Other than that, part numbers from each engine match.

Were you able to solve this completely? Is it still going into limp mode?

Thanks for your time!

 

Have you been able to exclude the fault in low pressure fuel pump (in the tank) or in the fuel line?

 

The intake and exhaust camshaft part numbers are also different between the '17 (5R1-050 / 5R1-020) and '19 (5R7-A10). Its possible the cam lobe driving the high pressure pump is taller or shorter, resulting in more or less fuel flow (pressure) than the ECM is expecting for a given control solenoid signal. It might even be stroking-out your HPFP, causing the chirping noise.

 

the '15 Fits had injector issues and i believe they were later upgraded , so the later models must be calibrated differently to operate with the newer parts . maybe your 2015 computor is not calabrated
to work with the newer fuel rails and or injectors on the '18 motor ?

 

Definitely sounds like a parts mismatch. I'd check the cam part # first and go from there. Pending all parts check out I'd then start the fuel system diag process (LPFP pressure at idle/WOT, damper/FPR functionality if they have them, FPS resistances and readouts, etc.). If they ran a different output injector on the two systems the computer could be opening them up calibrated for a diff system.- so your drop in pressure may be dumping fuel... Be careful with your cat...

 

i actually came across this thread right after doing a swap in a Honda fit and coming across the same issue, at 4k it will go into limp mode and on start up it would be giving me the code p0088 and then when driving and into limp mode it would give the code p0087 low pressure in the rail also would have a ticking noise at idle from the high pressure fuel pump. thankfully after I did the swap I held onto the old motor

2015 Honda fit
newer motor 2020 motor

what had to be changed to fix this issue was
2015 cams and 2015 fuel pressure housing assembly after this the noise subsided and everything functioned how it is supposed to, sofar have test driven without issue and on full throttle I don’t have any issues or codes.

my suggestion for you guys is to change back to the cams that match the high pressure fuel pump and also the housing needs to be the correct style. The casting look almost identical between the 2 versions but they are infact different I will attach some photos to assist with this.

 

Thanks so much for the info Kyle! We've been stuck.on this problem for almost a month now changing almost everything out. Ecu to match the engine for it, hpfp pump with housing, fuel rail, hose lines, sensors, and nothing changed. I did do the research on what's the same parts from the 15-17 fits vs 18-20. The differences mainly came to both camshafts, hpfp, hpfp housing, engine wire harness, and ecu. Everything else checks out to be the same. Only thing we didn't try was the camshafts which seemed the most likely culprit. Cams and hpfp are different on both engines and they should match each other, not vise versa.

Since then, how long have you had the car running and still no codes correct? Thanks again for the miracle reply!

 

so I did the swap last week and really only had time to work on it during the weekends to I did the cams and assembly today and after I heard the noise go away I was pretty sure there wasn’t going to be that issue anymore. After going for a 5 minute test drive trying to push it to see if the issue would happen again it did not. Around 10 miles of testing with no issues. I don’t believe it will come back.

I believe the cam shafts did play a role in it aswell as the cover/ hpfp assembly as I did notice there is a difference between the two I had as the bolt holes are positioned slightly at a different angle I’m not sure how much it effects it as I measured both and they seem about the same dimension wise.

 

Kyle, thanks for the info — you rock!

Unfortunately, I finally tossed the old motor this summer, and we’re still driving ours with the same issue. In case anyone’s wondering, we’ve put well over 20, maybe even 30k+ miles on it since the swap, and it doesn’t seem to be getting any better or worse.

I was originally hoping that whatever part was causing the problem would eventually fail completely so I could pinpoint it, but if it’s the camshaft, I suspect it’ll just keep going until this one ends up in the junkyard a few years from now—after my teens are done running it into the ground.

In the meantime, as long as you let it warm up in the winter and avoid flooring it too often, it still gets around just fine.