Public service announcement - 3rd generation Prius V 2011-2016 owners EGR clogging issue

TheWonderful90s
Thu, 28 Dec 2023 03:53:21 +0000
Maintenance/Repairs

Apparently these cars have an issue where the EGR ports in the intake manifold become clogged with carbon.

People recommend having the intake manifold cleaned and these ports cleaned at most every 100,000 miles, if not the whole EGR system.

The problem is that unlike most other cars that connect the EGR next to the throttle body where the exhaust gas flows with the rest of the air in to the engine, the 3rd generation Prius has a small port for each cylinder in the manifold. One of these ports will clog first, cutting that cylinder off from the EGR system, and diverting the rest of the exhaust gas in to the remaining cylinders. I believe this does not trigger a fault code. This leads to prolonged overheating of the affected cylinder and eventual engine damage and/or head gasket failure.

I’m surprised that a blocked EGR can do this. They must run the engine borderline too lean for fuel economy to begin with. I know little about EGR, but I don’t think other vehicles have separate per cylinder ports for EGR that can clog like this. So a clogged EGR can be detetected and/or corrected by the oxygen sensor without damaging just one cylinder while the problem goes undetected.

A lot of these cars still have under 200k miles on them. In the next few years this might became a much bigger issue, given the number of people who don’t research preventative maintenance. This just happened to someone I know with about 260k miles.

12 posts - 7 participants