Transmission not shifting?

P0172 = Fuel system too rich. It could be caused by many different problems and we have to go about performing troubleshooting but we will skip this first as P1259 might be the cause of it.

P0420 = Catalyst system efficiency below threshold. Could be a faulty catalytic converter or caused by P0172.

P1259 = VTEC system malfunction. Check your engine oil level and condition. When the VTEC system fails, power loss occurs and it would cause the transmission to shift erratically as the engine is struggling.

You should be due for an oil change if the oil level is correct.

If the last oil change was done long ago, then I would say get the oil changed now. If the change was recent, check the oil level and top up if necessary. Low oil level would cause the P1259 code to appear.

You just had the oil change?

Did you reset the trouble code and did it still show?

You might need to run the engine for a while to get it correct.

Erase the trouble code and then check and see if the same trouble codes comes back?

Btw were the spark plugs checked?

Hi juliani10,

In modern day vehicles anything that is installed are vital to the operations of the system and any removal is going to render the system useless.

Let us know what is your problem and we willl try to see if we can help you solve the problem.

Get a scan done at your local Autozone outlet and come back with the exact error code.