I have a car truck which has a 3.5l motor in it gives me a code PO401 and a PO431 and in the past says the number 1 and 3 and 5 Cyl. are Misfire. And all there cats are Emty.

Wow... Thats a lot of diagnostic codes. First... The cyl #1 misfire will cause the Engine to run rich giving you a rich running engine. Therefore the rich lean code. This misfire on cyl #1 can also throw a crankshaft sensor code as it will slow down engine rpm. I would change the spark plug and ignition coil to cyl#1 and have the codes erased and see if that solves the problem. If not, you then need to persue any codes that may reappear.

171 Sys lean bank 1 possibly o2 sensor 300, cyl misfire detected random cyl. 302 misfire cyl # 2. 304 cyl misfire cyl #4 with all 3 of these codes it might be time for new spark plugs and wires

1. Traction Control System Problems - Car Forums and Automotive Chat ...

   www.automotiveforums.com > ... > Toyota > SequoiaTraction Control System Problems Sequoia Car Forums. ... The VSC/ATRAC indicator lights are staying on and the system will inadvertantly ..... giving a bad reading following the replacement of the steering angle sensor with a new one.

PO 304 -cylinder misfire on #4--maybe-- could be any cyl,
the codes are not always accurate

PO401--EGR insufficient flow detected

I would start with whatever is causing the misfire. That seems to be the core of your emissions codes. Putting all codes together it seems to be clogged injectors vacuum leak. Seems to be causing stalling too.

Hi there:A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.

For example, a P0302 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #2; same condition in P0301 - cyl #1, P0303 - cyl #3 and P0304 - cyl #4.

A code P0300 (or 301, 302, 303 or 304) may mean that one or more of the following has happened:
Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer

About your possible solutions, if there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.


Hope this helps.

first PO171 o2 bank 1 s1 lean PO174 o2 bank2 lean
PO401 cyl 1 misfire
when an engine misfires the oxygen sensor will read the oxygen from that cyl sensor doesnt read fuel so every misfire is a air pump to diagnose we have to fix misfire first check the coil wires and plugs for cyl 1 use spray bottle with water run engine hot at idle spray wires with water if enging runs rough shakes or stalls then replace the wires dont spray with to much water if the wires are real bad you may not be able to restart engine

try this first once fix misfire clear codes and drive it

plz comment vote reply if you need more help

You need to have the ecm scanned for codes. The VSC and TRAC OFF lights are one just because the Check engine light is on. Once you clear the code in the ecm they will go off too.

2000 toyota highlander just had oil changed and VSC lightis on.
what to do

if your car give you i code thats says mutlipul misfire on number 1,2,3,or four cyl. that means that that cyl is not firing when its suppost to so if the code says number 3 cyl misfire or multipul misfire replace number 3 spark plug and coil pack and 80% of the time that will solve the problem.