Multiple Codes 2003 Nissan Maxima GLE

Nissan Maxima

Multiple Codes

Car has 152,000 miles. Car idles and revs fine while in park. When driving it clatters and looses power it you give it more than 25% throttle. I took it to Firestone and they did a diagnostic on it and it gave them the following codes:P0420- CATALYST EFFICIENCY BELOW NORMAL (BANK 1)…..P1574-ASCD VEHICLE SPEED SENSOR MALFUNCTION….P0300-MULTIPLE MISFIRE DETECTED….P0720TCM REVOLUTION SENSOR CIRCUIT MALFUNCTION. The mechanic at Firestone said that he does not know why the car is acting like this and referred me to a Nissan dealer. I am trying to avoid that because I know the cost would be astronomical for them to diagnose and fix it. It was running fine and then all the sudden it was like it is possessed. Any ideas?

The code P0420 generally means the catalytic converter isn’t functioning as it should. Now if you have been driving it with a misfire for a while it may have caused a larger issue. The unburnt fuel gets shoved out into the catalytic converter and can cause it to clog. If the converter is clogged it will act as you described. A back pressure gauge is inserted in the front O2 Sensor port to check for this. If there is more than 3 psi at 1500 rpm the converter is clogged. Generally if this is the case the car will perform normal at first and as the engine warms up the performance will fade. I have provided the code information below.

Nissan Code P1574

Description: Automatic Speed Control Device Vehicle Speed Sensor

Code P1574 Probable Causes

  1. Sensor or solenoid faulty
  2. Connector terminal contact is damaged or corroded
  3. Wire harness – Check harness for correct voltage, open, short to ground or short to voltage
  4. Update control unit software – Check for the latest control unit update
  5. Powertrain or Engine Control Module faulty

Nissan Code P0720

Description: Output Shaft Speed Sensor Circuit

Code P0720 Probable Causes

  1. Sensor or solenoid faulty
  2. Connector terminal contact is damaged or corroded
  3. Wire harness – Check harness for correct voltage, open, short to ground or short to voltage
  4. Update control unit software – Check for the latest control unit update
  5. Powertrain or Engine Control Module faulty
  6. Transmission system malfunction

Nissan Code P0420

Description: Catalyst System Efficiency Below Threshold Bank 1

Code P0420 Probable Causes

  1. Sensor or solenoid faulty
  2. Connector terminal contact is damaged or corroded
  3. Wire harness – Check harness for correct voltage, open, short to ground or short to voltage
  4. Update control unit software – Check for the latest control unit update
  5. Powertrain or Engine Control Module faulty
  6. HO2S sensor contamination/damaged
  7. Exhaust leaks or restrictions
  8. Catalytic converter damage
  9. Catalytic converter improper operation

Nissan Code P0300

Description: Random – Multiple Misfire Detected

Code P0300 Probable Causes

  1. Vacuum leaks, damaged hoses or improper routing
  2. Fuel contamination
  3. Ignition system – Ignition module, coil, spark plugs and wires
  4. Fuel system
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