Demystifying P0170 Fuel Trim Malfunction Causes, Effects, and Fixes

'P0170' Fuel Trim Malfunction Bank 1 Legacy Forum. This thing comes and goes on me time to time with weird idle supposingly it happens if you put to much gas in the car or don't lock the gascap properly. You are running outside optimal fuel trim. There is a probably an air leak somewhere in your intake system (MAF, vacuum leak, o2 sensor not ... 16554 P0170 035 Fuel Trin, Bank 1 Malfunction Possible causes: Air leaks - Map, TB gaskets?? Lambada - Clean or Replace any other possibilities? Well-Known Member ... The P0170 is based upon a rich mixture that the PCM is trying to lean out when it reached the end of its lean range. Perhaps ... The Toyota FSM says the P0170 code for the 1995 LC is not set until fuel trims have reached +/- %35 and my trims are not even close to that. The OBD-II fault code P0170 means that the Powertrain Control Module has reached its operational limit with adjusting the air to fuel ratio, ... Minivan, SUV, & Truck - P0170: Fuel trim malfuction (bank 1), P0172: System too rich (bank 1) - My Odyssey (2001) is running rough, ... The p0170 code refers purely to the fuel mixture (air/fuel ratio) but without stating which way it's going. p0171 is mixture to lean and P0172 is too rich. Pull the vac line off the fuel pressure regulator and see if any gas drips out ... this means a bad regulator and will cause trim code..