Code P0172, engine light and VTM-4 on the dash?

SEEKAN

MEMBER
2007 HONDA PILOT
3.5L
6 CYL
4WD
AUTOMATIC
142,000 MILES

Have been seeing Engine light and VTM-4 lights on and off for the past few years. When scanned it showed "P0172 Rear bank (bank1) fuel system too rich". Is this due to a bad MAP sensor? I tried to clean once a year ago.
Any guidance on how to fix it? If I were to replace the MAP sensor, is it recommended to go with OEM or any reputable aftermarket model?
Thanks

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

Because only one bank is affected, it won't be a map sensor. That would affect all cylinders.

I suspect either you have a faulty fuel injector, or someone tried adjusting the valve lash and has caused a problem.

What I would start with is to simply try using a quality fuel injection cleaner. See if that changes things. If it doesn't, the next step would be to check fuel pressure and pressure drop-off. If there is a stuck injector, pressure will drop faster than it should once the pump is off.

Here is a link that shows how that is done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you look below, I attached the manufacturer's procedures because they are a little different than the link. The fuel pressure specifications are included in the directions.

Another idea is a faulty oxygen sensor for that bank. We can cross that test procedure if needed.

Let me know what you find.

Joe

See pics below. Note: Most parts stores will lend you the fuel pressure gauge for testing.

Images (Click to make bigger)