2001 Ford Focus 1.6 - P0172

Hi,

First off, as this seems to a be a US site I'll start by saying I'm in the UK so the car is obviously a UK car. Hope you can still help out.

I have a 2001 Ford Focus with a 1.6 litre engine. I have an OBDII reader and using Digimoto Lite I got the results shown in the image. They were taken at idle/tickover after a 20 mile journey so the car was properly warmed up. I also had the engine warning light on. The reader gave me the code P0172.

I had the light before and called the AA (recovery service here) out. They told me running rich on bank one and read my lambda sensors. The guy told me bank 1, sensor 2 wasn't sending any data and to clean or replace that (haven't actually got round to that yet though).

Plugged my reader in this time to check it myself and it's telling me sensor 2 on bank 1 is sending data but sensor 2 on bank 2 isn't. Do straight 4 cylinder engines have a bank 2? If they do, can anyone tell me where I might find this sensor?

I read on here that oiled filters like K&N's can set the MAF off and since I re-oiled mine last night that may be what gave me the light again today, combined with whatever lambda sensor isn't working right.

Last thing, can anyone tell me if the rest of the info in the pic is as it should be or not?

Clean/check MAF as well as checking the circuit and connections.

Replace the K&N with a paper filter.

Check for vacuum leaks as well as exhaust leaks.

Disregard Bank 2 info.

Good luck and keep us posted.

Hi, I'm not sure the exact system your car operates on it could be a little different between U.K, N.A. versions.

By the fuel trim readings your engine is definately running very rich at idle speeds. You also don't have an MAF reading so the engine must be running on fuel tables or you have a MAP sensor instead, I'm not sure if 4.5 PSI is good or not. Also your ignition timing looks overly advanced (is that 64* or 6.4*?).
Suggest , fix the MAF problem (looks like you have an electrical connection problem or the MAF hotwire is broken or totally contaminated).
Check fuel pressure at the fuel rails, it looks like you might have a possible defective fuel pressure regulator if the fuel rail pressure reads too high. You could also have a blockage in the return line (if it uses the returning fuel system). Also check if the vacuum hose is functioning properly. Fuel pressure at idle speed should be lower than at opened throttle.
Another possibility is that you have leaky/sticking injectors, is the car hard to start when hot?
I would also get shot of that K & N filter they may be O.K. for performance cars but for stock cars you'll get MAF contamination problems & also they don't filter the induction air system thoroughly compared to paper filters.

Yet another possibility is purge valve leak in your evaporative fuel vapour system . Induction vacuum can draw fuel fumes direct from the carbon cannister, when infact the purge solenoid should be closed, although you should get a code for this.
O2 sensor can also stick rich; did you notice the O2 sensor Bank1 S1 voltage reading fluctuate between 0.1- 0.9 volts ? 14.6:1 fuel ratio is maintained by constant switching from rich to lean, if this does not occur you get a code. It appears you don't have a code yet. The engine has to be at normal operating temp to get these fluctuating or rich/lean readings.

4 cylinder inline engine generally has only 1 bank of injectors, so the Bank 1 sensor 2 is actually a Catalyst sensor it checks for normal operation of the converter. It does not affect fuel/ air ratio.

Good Luck Aeroman.