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P0400 service engine soon

(1998 Chevrolet Metro)
in Parkville, MD on May 28, 2010
Idle started going up and down worst when head lights in on position. Then service engine soon light came on. took car too jiffy lube hooked up to computer came up p0400
Displaying 1 answers & 2 comments
Popular Answer
on June 25, 2010
Diagnostic Trouble Code (DTC) P0400 stands for EGR Flow Malfunction. Sometimes this code is set when the Manifold Absolute Pressure Sensor detects a pressure change too small or too large.
on June 26, 2010
Fernando,
Can u help with a location for this pressure sensor. Idles getting worst but runs fine.
Thanks Rob
on June 26, 2010
The MAP sensor is located on right side of firewall.

Replacing the MAP sensor could not be the solution. There are more variables that could set the DTC P0400. Some diagnostics are;
*Check all vacuum hoses connections, inspect for leaks, clogs or incorrect routing.
*Check for malfunction in the EGR solenoid vacuum valve or the EGR by-pass valve.
*Check for a poor PCM electrical connection.

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