Howdy, I've been around cars for awhile but recently moved to California and bought a 2015 Prius 1 and a 2013 Highlander Hybrid. Both have been rolling for a few thousand miles with no issue getting close to their sticker mileage in the Sierra Nevada mountains. Until... both now have minor issues that do not seem to be affecting nikeage or performance for this post I will focus on the 2015 prius. It is throwing code p0403. Ive read this is in regards to the egr system, likely electrical. I have checked the efi#2 fuse, it is good I have checked the ohm readings on the valve motor, all read between 20.3 and 20.7 ohms. I appear to be gett8ng at least 11.64 volts from all the pins. I have park the car till I can get this resolved. Is the next step to pull the parts and prepare the brake cleaner for the egr valve, the egr tube and possibly the egr cooler?
You are on the right track with your electrical tests. I would probably repeat them and then ohm out the egr to ecm wires. With Techstream you could try the egr step test as well which measures changes in intake pressure as the valve opens and closes. However with that code its most likely not moving and the system can detect an electrical issue like an open or short.
I tested the ohms on the plug on the egr motor, still read 20.5 for the shown pins. Tested resistance on ecm-ecr connector wire, all pins registered well under 1 ohm on shown pin connectors. Tested all pins for shirts, found all pins OL on 20k ohm setting, no shorts detected. OHM reading Voltage showed 14.45 upon turn on but engine did kick on.
I dont have much experience with e8 bolts. The one holding the engine block to the egr came out with some difficulty. The one connection the egr cooler to the exhaust pipe though, well. After a few explectives I have managed to make this job harder. See photo fir example of oafishness.
If you remove both lateral studs, one at the EGR valve, the other through EGR cooler’s lower bracket (access difficult), then you can leave the rearmost pair of longitudinal studs, that connect EGR cooler’s end flange to exhaust manifold, still manage to extract the cooler. Side benefit is that pair of studs will keep the gasket in place, avoid it dropping down during removal, and align it during reinstall. when pulling out the EGR assembly with rearmost studs still in place, it will bump into a tube above (gas vapour return?), but loosening its hold down bolt will give sufficient clearance.
