Reader Question
Hey Austin, I was told the EGR valve in my car is what is causing my check engine light to come on and the engine to run bad. I hear this weird noise as well, not sure if it is related or not.
Any info will be helpful
Doug
Howdy there Doug,
What symptoms should you expect with a bad EGR valve?
Exhaust Gas Recirculator
That depends on a few different things. If the EGR is a vacuum model or Digital (electronic), how it failed (loss of vacuum, loss of electrical signal), if the EGR is stuck open or closed. I will try to address each of these failures.
A vacuum EGR that is stuck closed or has an EGR port carboned closed (full of carbon) will have no running symptom, but will usually set a code for lack of EGR flow. An electronic EGR stuck closed will also have no running symptom, but will set a code for EGR pintle response. (more on that later)
An EGR that is stuck open(vacuum or electronic) will make the engine run rough or die at an idle, but will run normally at higher rpms. This will not set usually an EGR code on a vacuum model, but will on a digital EGR.
This valve is almost completely stopped up with carbon (you can see the pintel in the middle…that little shiny little pin in the middle of the gunk)
Any noises?
No noises are usually associated with the EGR other than when stuck open the engine will be gasping for air because exhaust gases are being reintroduced to the cylinders at an improper time. Kind of a chugging noise.
Common engine codes associated with it?
Common EGR codes are:
- P0402 EGR FLOW EXCESSIVE
- P0403 EGR CONTROL CIRCUIT
- PO404 EGR CONTROL CIRCUIT RANGE/PERFORMAN
- P0405 EGR SENSOR ‘A’ CIRCUIT LOW
- P0406 EGR SENSOR ‘A’ CIRCUIT HIGH
- P0407 EGR SENSOR ‘B’ CIRCUIT HIGH
- P0408 EGR SENSOR ‘B’ CIRCUIT LOW
- P0409 EGR SENSOR ‘A’ CIRCUIT
On pre OBDII cars code 32 indicates an EGR problem and a code 31 indicates a EGR valve position sensor problem. Other codes for pre OBDll cars include 32 lack of EGR control, 34 indicates no EGR flow, and 84 which is a electrical circuit fault.
Vacuum vs electric? I will try to explain the differences. Vacuum is controlled by various means such as the earlier models were controlled by a thermoswitch and ported to venturi vacuum, which means it only came on when the engine was warm and the rpms were above a certain level.
Later models are basically a solenoid controlled by the engine computer that can tell if the EGR is flowing by two methods. One is a feedback type and the other looks for a change in the 02 sensor values.