I have a 2006 325I with a P0301 error code in addition to P1553 what is the most likely reason

A reasonable explanation and possible rectification suggestions on the link below.

https://www.obd-codes.com/p0301

Here's a link on your P0301 code. P0301 OBD II Trouble Code Here's the link for the P0401 code. P0401 Saturn Exhaust Gas Recirculation Flow Insufficient your egr passage may be blocked.

misfire cylinder number 1 need to check wiring coils plug for the number 1 cylinder
https://www.engine-light-help.com/P0301-check-engine-light.html P0301 OBD II Trouble Code Fixing Misfiring Engine P0301

Check out related help links to troubleshoot these common error OBD code noticed on many brand vehicles:------
1998 GMC K1500: OBD Error Code P0430? http://schematicsdiagram.blogspot.in/2012/06/1998-gmc-k1500-obd-error-code-p0430.html

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OBD code P0301, P0430 and P0174? http://schematicsdiagram.blogspot.in/2012/02/obd-code-p0301p0430-and-p0174.html

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These will help.
Thanks.

The error code p0301 ,This code is related to misfire.The cylinder is misfiring. p0301 this is the indication of cylinder number 1 ,that is misfiring.If the code comes up as p0300 this is the indication of random misfire from all the cylinders.But in your case its indicating p0301 this is indication of cylinder 1 misfire.Check cylinder 1 and replace the faulty cylinder 1 to clear the fault.The spark plugs and the wires connecting to spark plugs also needs to be checked. Keep updated with any more query.Thanks.

p0301 is Cylinder 1 Misfire. Check fuel injector,Spark plug, plug wire, ignition coil.

p0326 is the Knock sensor (Combined with above code I'd check the fuel injector on #1 cylinder)

Generic code is Cylinder 1 misfire

Code P1399 is specific to Honda - it is an error code for "multiple variable misfires detected". P0301-P0304 are common OBDC codes for all cars, specifically "misfire in cylinder X".

You will get the P0301-P0304 codes on your OBDC reader when you plug it in (if actually errors), but will only find the P1399 if you select Honda as the manufacturer.

Just got these errors today on my CRV 2000. Now I have to figure out what is causing two of the cylinders to misfire.

DTC P1553 Barometric/manifold pressure signal ratio out of range

Trouble Code: P0301

Cylinder Number 1 Misfire Detected
Possible Causes:


Air leak in the intake manifold, or in the EGR or PCM system Base engine mechanical problem that affects only Cylinder 1 Fuel delivery component problem that affects only Cylinder 1 (i.e., a contaminated, dirty or sticking fuel injector) Ignition system problem (coil, plug) that affects only Cylinder 1