Hello fit freaks.

We have an 07 Base with 206k. Some background: I was getting cyl 3 mis-fires and after a week of failed troubleshooting I took it to a shop. The alternator was going out, coupled with a bad coil pack was showing as a mis-fire (I miss-number the cylinders and spent my time troubleshooting cyl 2 not 3 )

I changed out the plugs and injectors, adjusted the valves (which the mechanic verified), and checked compression. The mechanic did the alternator, 2 coil packs, and belt. He also mentioned a code might come back on (but I don't remember which) and I'm fully capable of replacing the O2 sensor. It took a few days to get this code though, and I suspect if it were the O2 I would have got it right away.

So now the light's back on, it's saying P0172, my Longterm Fuel Trim is -22% and alldatadiy.com tells me for a P0172: if fuel pressure is ok, check valves and replace injectors. I know the valves and injectors are good... so should I pay to have the fuel pressure checked?? Will the rear O2 sensor fix this? Is there a way to dial it in before spending $200 on a part?

thanks!!!

 

I bought a denso (OEM) upstream O2 sensor and never installed it. It is new sealed in the box with the copper anti seize tube (unopened). If you want it, PM me.

 

The a/f sensor detected rich condition (F/t over -20%) and set the code. Next step is to verify if condition is actually rich. Get your idle CO and O2 tested on smog station and if CO is high and O2 is 0 the sensor is ok and you have to fix the evap purge valve perhaps (open all times)
If CO is low and O2 is high, the car runs lean but sensor indicates rich, so the a/f sensor is bad and need to be changed!

 

not sure if you’re still active, but I’ve been fighting the p0172 CEL for months to no avail. You mentioned the smog ratios, can you give me more insight of how to diagnose reading the fuel trims?

My trims stabilise on decel and goes a little lean, then it slowly climbs back up to constant -29.97 from idle and any acceleration.

Is the relationship of primary and secondary o2 sensors supposed to read similarly to confirm the afr going through the cat? Ie. When on accel voltage is o2S1 .87 vs o2S2 .87 - but on idle it’s .87 vs .2.

I’ve literally triple checked and replaced the common culprits (o2 sensor, EGR valve, purge valve, lash adjustment, coils, injectors, fuel filter, fpr, pcv valve). No visible vac leaks in the bag, but haven’t done leak down test yet. 0 drivability issues other than that CEL. Truly stumped.

im turbo (top fuel zero 1000 bolt in with hks fcon piggy back) - starting to think it could be the piggy back?

car drives well, getting 6.5-7L/100km AUDM Honda jazz gd3 (Vti-S). I need help!