Skip the auto shop - Our mechanics make house calls

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?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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: my car does not start.

The immobilizer is active and will not allow the ignition to turn on or let the vehicle to crank. Try your second extra key to see if it will allow the vehicle to start. If it still does not work...

Q: Can i retrieve CEL code from car ... forgot what code it hade in my car .. put headgasket sealer and i erase the code ..

Once a trouble code is erased, it cannot be retrieved. The engine controller does not have a "recycle bin" like they have on Windows. If the car still has a problem, the code will come back up after some driving....

Q: my car makes a humming noise under the hood while I'm driving and parked. could it be a fuel pump issue or ignition problem?

A humming noise can be the engine electrical cooling fan. The fuel pump is in the rear of the vehicle so that is not as likely to be the cause. To pinpoint the fault, I would have a certified technician...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...