I have a '96 SL-1 with the Service Engine Soon light on. I bought a cheap code reader and it comes up with 1406. The book with the reader says that is "Differential Pressure Feedback EGR (DPFE) Sensor Downstream Hose Off or Plugged". Which do they consider downstream, the engine side or the exhaust side? The hoses appear fine. I do have a rusty exhaust pipe that is leaking, though. Could the reduced backpressure cause this code? If replacing the pipe will fix it problem, I'll hold off on fooling with the EGR (since it's about $150 and I have to fix the pipe anyways). Thanks, Buster
DTC 1406 on a '96 SL-1 (with rusty rear doorsills)
Nov 15, 2003
4 Replies
That's the wrong code description - P1xxx codes are manufacturer-specific, GM doesn't use a DPFE setup - that sounds like a code for a Ford. P1406 for GM seems to be a problem with the EGR pintle position (actual pintle position as indicated by the sensor inside the EGR valve doesn't match the commanded position).
I don't see the exhaust pipe affecting that. However, those linear EGR valves tend to be somewhat pricey, you might want to get someone to take a closer look at it with a scan tool and compare the EGR valve position readings to make sure that's what's going on. It probably is the valve that's gone bad though. It's possible it's just jammed with a piece of carbon or something, but I wouldn't count on it.
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