Q: 2004 Nissan Altima- Won't move when the code reads p0420 on the scanner. Did my transmission go? Is it my catalytic converter like code said?

asked by on

2004 Nissan Altima 4 cylinder. Last night my check engine light came on. I drove to work this am and went to autozone and service code came back as P0420.. When leaving work my brake light and battery light came on in addition to check engine light while driving. Stopped at daughters daycare to pick her up and car would not start. I was able to get a jump and car started but when I press on gas it does not move. Did my transmission go? Is it my catalytic converter like code said? What steps should I take? Please help!!

My car has 143000 miles.
My car has an automatic transmission.

Hi there. The code P0420 means that the catalytic converter is below threshold and cannot burn off any emissions in the exhaust stream. The O2 sensors have pickup this fault and put the engine into limp mode. As for the vehicle not moving, the exhaust may be plugged up causing the engine to not breathe properly. Put the vehicle in drive and set the parking brake. Fully step on the gas pedal to the floor and have someone feel the exhaust pipe. If there is very little pressure coming out of the pipe, then the catalytic converter has plugged up and needs replaced. If the pressure is normal, then the computer may have locked the transmission out of the drive cycle. If you need further assistance with your vehicle not moving due to the code p0420, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. 2004 Nissan Altima- Won't move when the code reads p0420 on the scanner. Did my transmission go? Is it my catalytic converter like code said?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Permanent fix to steering wheel lock issue

Hello. You can indeed disable the steering lock system by removing the fuse, however you would need to get the vehicle started before doing so. The steering wheel lock system uses an actuator that moves back and forth to lock...

Q: what causes noise on power steering when starting car?

A worn power steering pump will make a whining type sound. It usually starts as a whine when cold and diminishes somewhat once warmed up. If the reservoir is full and tehre is no power steering fluid leak, it may...

Q: I having trouble cranking my car due to a sensor , how much will it be to replace. altima 2009 nissan

If the check engine light has illuminated, and the code refers to a sensor, there are quite a few possible repair outcomes. The cost can't be determined until the code is read and the EXACT fault is identified. Keep in...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.