The C1438 Code plays important role for solving the car engine problem but it is necessary to read the real meaning of the code. Your car manufacturer has set a meaning for your car engine and you have to know that meaning. Do not use different meaning of the code from different car manufacturer. The poor running indications are reliable with a MAP sensor fault. In addition, in some cases, a bad MAP sensor will not toss a code. If you know how to solve the car engine problem and you have all necessary information and tools, you can try to solve the engine problem.