p0401
 

check engine light came on. 2.2 le 180,000 miles. last year replaced egr to solve a stalling problem. tested it with vacuum, stalls motor. replaced vacuum modulator. still throws code. by the way, throws 2 codes, but the same p0401 comes up when scrolling to second code. car runs fine. do i need to replace vsv or will car be fine as is? emmissions over a year away. any help as always appreciated.

p0401
 

oh, its a 1999 camry.

What are the codes?

The P0401 code means the EGR SYSTEM is not operating. The engine quitting when the EGR valve is manually operated only means the EGR VALVING is working OK. This being the valve works and the EGR exhaust passages are clear allowing the gas to enter the engine in mass and stop it.

The VSV turns engine vacuum on to operate EGR system. When valve is on, the EGR modulator operates and responds to engine vacuum changes. The modulator controls the EGR valve.

Problem could be the VSV, modulator or hoses between them. VSV is turned via 12V DC. Can test manually. When VSV off, the vacuum hose going to the modulator is vented to atmosphere turning the EGR system off.

VSV is closed when:
Deceleration/throttle valve closed
Light engine load
Idle
4,400 rpm+
Full throttle
Engine warm up

so the system uses the egr valve, the vacuum modulator, and the vsv. the egr valve is almost new and working, the modulator is replaced, and all that is left is the vsv which is very hard to get to and it's very cold outside. if i can't notice any difference in the motor's performance, will i hurt anything? both codes are p0401.

It's OK to drive. The mixture may be slightly lean. Suggest not hot rodding the engine or operate at high RPM (trans manually downshifted to rev engine), trailer towing, etc.

The MPG may drop and emissions go up.

thanks, joey