My 2012 GMC Denali 2500HD just threw this P140D code, check engine light came on and then the Service Emissions System was displayed. That code appears to be the EGR valve, so I'm assuming it needs to be replaced, but the question I have is there is also a EGR bypass valve does this code pertain to one or both of these valves, yes it would be nice to just do a delete but unfortunately I live in a state that requires emissions testing.
Threw P140D code
- Thread starter r_olsen
- Start date
140D is the egr valve itself not the bypass. It is a low voltage code that pops on close, this doesn’t necessarily mean the valve is bad, check for chaffed wires along the motor where the harness runs.
If you can’t find a short then the valve could cause that issue.
It’s best to have a buddy with a tech2 to command the valve open and closed at 90% and verify proper voltages.
Ignition OFF, disconnect the harness connector at the Q14 EGR Valve.
Ignition ON, connect a test lamp between the EGR Motor Open Control circuit terminal 6 and ground. The test lamp should not illuminate.
¤If the test lamp illuminates, test the Motor Open Control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
Command the EGR Motor to 10 % with a scan tool. The test lamp should illuminate.
¤If the lamp does not illuminate, test the EGR Motor Open Control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM.
Ignition ON, connect a test lamp between the EGR Motor Close Control circuit terminal 2 and ground and command the EGR Motor from 0-90 % with a scan tool. The test lamp should illuminate and decrease in intensity with each increase in command.
¤If the test lamp does not illuminate or respond as specified, test the EGR Motor Close Control circuit for a short to voltage, an open/high resistance or a short to ground. If the circuit tests normal, replace the K20 ECM.
If all circuits test normal, replace the Q14 EGR Valve.
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