Fixing Code P0170 Fuel Trim
 

Its a 1995 Es300
I am currently combating code P0170 fuel trim, so if anyone has any info on how to fix this I would be eternally grateful. I have taken it to firestone and they have performed a smoke test and repaired vacuum lines and the code came back. I have replaced plugs, coil packs, injectors, Mass Airflow sensor, fuel filter and fuel pump. I am thinking that it may be something electrical.

Hello,

Did you try to reset the code?

What parts did you use as replacements? From the list, it appears that you replaced half of the car already, burying more than twice the cost of the car itself.. Good quality injectors and coils are quite pricey, hence the reason for my question. There are a ton of counterfeit parts on eBay or Amazon, and aftermarket parts other than Denso can result in a lot of misadventures.

Right now the task is to see if you have a Rich or Lean condition, since the DTC code provided is quite general and doesn't tell a whole lot. For that, you will need a scan tool capable of reading Engine Live Data - check the current values for your Long Term and Short Term fuel trims (LTFT and STFT), as well as your O2 and MAF Sensor readouts, which should give a general understanding of which way to go from here. Other than that, you can also try disconnecting B1S1 O2 Sensor, which should be on the Exhaust manifold in the back of an engine, towards the firewall, see if it will clear out a P0170 code, if so, then you will likely need a new O2 sensor.

Hope this helps and best of luck!

Yes I have reset the code after each replacement part. I am not sure about the injectors and coils but the plugs and all O2 sensors are Denso for sure. I currently have the vehicle in the shop. Will update post once I pick it up. Thanks

I think we must be related?
So your code could be caused by so many different things. A vacuum leak, weak fuel pump, old O2 sensor, exhaust leak, etc. So u don’t want to start throwing parts at it unless you have some evidence it’s likely the cause. Can u post what the fuel trim % is at a few different RPMs? Depending on if the get better or worse at higher rpms can point to where the problem is.

Update on my P0170 Fuel Trim code: It was actually a bad fuel pump that firestone had installed just about 4 years ago. She seems to riding along just fine now. Thanks for all of your help.