I was driving along using radar cruise and then all of a sudden the Check VSC/CEL/TRAC OFF lights all went up. I took it in and it was giving 2 codes - P0456 which they said was from a crack in my gas cap, and P1578 which is for the braking system. The brakes have been doing this weird thing where if I'm stopped at a light, the car will start to inch forward and it will require more foot pressure to keep it stopped. Is this the brake booster or master cylinder going bad? brake actuator? I'm taking it back to be diagnosed in a little over a week when they have time to check it out. It sounds like it could be anything though. They reset the lights and they haven't come back on....yet. Car is a 2004 UL with 209k miles.

 

Sounds like a leak in a vacuum line connecting to the brake servo, or possibly a vacuum leak inside the servo itself.
If the pedal does not move without pushing harder, then the master cylinder itself is OK.
Check the hose that connects to the servo as it may have gotten old and cracked.

 

Thanks. I went to the shop and cleared the codes and ran the diagnostics. It came back with P0354. Not sure I didn't swap it correctly or not. Let me rerun it again.
The diagnostics run by Brake Masters came with WITH THE CODES P0354, P0AOF, C1241, C1377

 

Thanks. I went to the shop and cleared the codes and ran the diagnostics. It came back with P0354. Not sure I didn't swap it correctly or not. Let me rerun it again.
The diagnostics run by Brake Masters came with WITH THE CODES P0354, P0AOF, C1241, C1377

 

A P0354 code means that the ignition coil or coils are not functioning properly and that there is an electrical problem with them.
A P0A0F engine code means that your car's engine has failed to start.
C1241 LEXUS Low Battery Positive Voltage. Possible causes : – Low Battery Charge. – Faulty Battery. – Faulty Charging System.
C1377 is ABS capacitor malfunction and C1241 is ABS Low or High Power Supply Voltage.

I would start off with a brand new battery, then reset the codes and go for a drive with it.
If the codes return then you will need to investigate each one individually.

 

A bad battery would possibly make the car freak out like it is currently doing, the electronics on these cars are very touchy.