What am I missing??? Working on Smog for my 597,000mile Prius I’ve got it down to two remaining codes I don’t seem to be able to resolve. P1451 and P1453 Both having to do with the EVAP system. P1453 shows up first after a couple drive cycles The code: Fuel tank Pressure relief valve Malfunction. P1451 shows up in a couple more driving cycles The code: EVAP emission control system vent control circuit. I had these codes and P043E, P043F, P1453, P2401, P2402, P2419. So i replaced the gas cap and took the emission system and gas tank from a known emission healthy 2006. Keeping only the wiring harness replacing everything else, because there is a slight difference between the gas tanks and the Evap purge valves 05 has two contacts and the 06 has six. The canister is also slightly different because of the charge in the shape of the fuel tanks (FYI). All the codes resolved except the P1453 and P1451. With wthe help of a U-Tube video I learned of a test, so I measured voltage between the sensor wire to ground on the wiring harness leading to the fuel pressure relief valve and got 5volts (meaning the wire harness is good and the valve not) so put the 05 sensor back in as a test and no change. Same codes same drive cycles. Does anyone see what I’m missing? iPhone ?
P1451 and 1453 show up in my reference as fuel tank pressure sensor P1451 Fuel Tank Pressure Sensor Range/Performance P1453 Fuel Tank Pressure Sensor High Input Both say suspects are the sensor, wire harness or ecm. DTC P1451: Pressure sensor abnormal voltage fluctuation or being constant If the pressure sensor output voltage fluctuates rapidly for 10 seconds, the ECM stops the EVAP system monitor. The ECM interprets this as the pressure sensor voltage fluctuating, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC. Alternatively, if the sensor output voltage does not change for 10 seconds, the ECM interprets this as the sensor voltage being constant, and stops the monitor. The ECM then illuminates the MIL and sets the DTC. DTC P1453: Pressure sensor voltage high If the pressure sensor voltage output is 4.9 V or more, the ECM interprets this as an open or short circuit malfunction in the pressure sensor or its circuit, and stops the EVAP system monitor. The ECM then illuminates the MIL and sets the DTC (1 trip detection logic).
That's odd. I'll check to make sure my file still says Toyota Repair Manual at the top.... Yup, still says it...…...
Here you go....found this..go to page 322 http://stuff.jaygroh.com/prius/Prius%20Info/Official%20Toyota%20Info/Repair%20Information/Repair%20Manual/ES%20-%201NZ-FXE%20Engine%20Control%20System%20.pdf
I wrote this up and sent it in to a Toyota tech @ JustAnswer. He said that using a gas tank from a 2006 and a purge pump from a 2005 was “likely” my problem. That the ECU was possibly looking for different values. He said I should put the parts from a 2005 back. It got me thinking I had gotten P0606 earlier in my quest to get rid of the emission codes and had put the 2006 ECU into the 2005. So just for fun before swapping the tank back (a tank is a tank right?) I took out the glove box unplugged the 2006 ECU and plugged in the 2005. Something STRANGE occurred Using my Veepeak code scanner with the 2006 ECU, I had been monitoring 1.) Commanded EVAP purge % 2.) EVAP pressure measured in Pascals 3.) Absolute EVAP pressure measured in PSI Now, with the 2005 ECU there was no Absolute EVAP pressure to be monitored?? Could this be the difference between 2005 and 2006 ECU’s ? I’ve driven it 8 drive cycles and no codes and no lights, however the EVAP test is still incomplete. Hope this helps someone. iPhone ?
