What's the p2004 code Mazda 6?

The P2004Code on a Mazda6 expands to the error message Intake Manifold Runner Control (IMRC) Stuck Open Bank 1. Bit of a wordy old thing, isn't it So, working backwards, Bank 1 is the bank of the engine that contains the number one cylinder. The IMRC is an actuator for that bank, and ... Is stuck in the open position. OK, I know, that's still confusing. In a nutshell, there are little metal flaps that control the airflow to Your cylinders, and, of course, air's needed for the ignition cycle. This message is reporting that the flap in question doesn't appear to be functioning correctly, as the ECU isn't detecting a change in manifold air temperature with the repositioning of the flaps, when it should be. Often, it'll take multiple ignition cycles for You to see this if the IMRC is failing. You'll notice reduction in engine performance, especially at low RPM levels, often occurs in tandem with this diagnostic trouble code (DTC).