Q: Check Engine Light is on - code P0405

asked by on

In the last year and a half my husband has changed the EGR valve twice, cleaned out the ports and also the fuel pressure regulator, but the check engine light comes back on after just a few miles. The code is p0405 - what else could be causing the light to come on?

My car has 129050 miles.
My car has an automatic transmission.

This code could be caused by the EGR valve, the EGR valve position sensor, a wiring or connector issue, or even a problem with the PCM. P0405 is set when the PCM sees a voltage reading below .35 volts. So, there are actually several issues that can cause this reading to be low.

There is a long diagnostic flow chart to diagnose this particular trouble code. It would be best to consult a certified mechanic, such as one from YourMechanic, who will have access to the tools and flow chart needed to diagnose why the Check Engine Light is on and what is giving rise to code P0405.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Check Engine Light is on - code P0405

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Why do car rpms bounce when I put it in drive?

This may be a sign of a dirty or failing mass air flow sensor. The mass air flow sensor is a unit in the intake system that monitors air intake as it is mixed with fuel prior to being injected...

Q: Horn is extremely sensitive after putting it back in the steering wheel.

Hi there. See if the springs were installed properly to the horn. Also, check to see if the wiring to the horn was tight and not loose. A return spring on a horn button will sound the horn sooner with...

Q: Q: Car going into Limp Mode

Your problem may be something simple or more complex. The first thing that needs to happen is for the Diagnostic Trouble Codes or DTC's to be read and addressed. There are only a few things that can put your car...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.