Toyota 4GR-FSE code P0172 "bank one rich"

There are 3 receipts on the passenger seat for oxygen sensors being replaced by another shop - not sure what code they were getting.
Fuel trims are pretty extreme, fault code P0172 for "bank 1 too rich".
MAF sensor is quite low at 2.8 g/s considering the size of the engine. The one spark plug I pulled out looked good.
Fuel pressure is 4000kpa at idle, 9000kpa at 2000 rpm - not sure what it should be?

Does it seem low on power or sluggish?

I haven't taken it for a drive yet. What would it suggest if it was?

Clogged cat

Thanks - would that make it rich on both banks? Bank 2 fuel trims are also pretty high.

Hi Desmond,

2.8 g/s is what i´d expect in 2.5L engine at idle (normal to me).

Also fuel pressure is normal (from 4 to 13Mpa), depending on demands.

Best regards

guafa wrote: Hi Desmond,

2.8 g/s is what i´d expect in 2.5L engine at idle (normal to me).

Also fuel pressure is normal (from 4 to 13Mpa), depending on demands.

Best regards

Thanks for the info - I imagine we need to first check whether the correct O2 sensors have been fitted then perhaps check for back pressure in the exhaust - unless there is a way to diagnose a clogged CAT in live data?

Do the downstream sensors agree with the upstream sensors? As in, if the trims are crazy rich, then the downstream sensors should show fully rich, too.

There's a Toyota bidirectional test that'll let you take control of the fuel trims directly for diagnostic purposes. Snappy labels it 'A/F Lean/Rich', not sure what Autel calls it. :silly: The test will shift the fuel trims negative and positive by a calibrated amount so you can make sure all sensors respond rationally.

We don't get that engine in the States, so I'm not familiar with the fuel system on this one. If you pull the dipstick, does it smell like gas. Possible fuel getting into the crankcase.

Despite your 2.8 g/s reading, I'd still be tempted to give the MAF a cleaning anyway.

Thanks Tyler, some good tips. I have the week off but will forward this info to my work to check.