Emission Test Failure

[Walter17]

Hi guys, I took the test yesterday again and failed. This is 95 Maxima GLE with 318,000 km. Even though I’m getting the following DTCs the only engine performance concern I have is an occasional cold stalling:

13 (engine coolant temp. sensor)34 (knock sensor)53 (front heated O2 sensor-right bank)

I would really appreciate any feedback on what my repair list priorities should be. Given the car mileage, I don’t think it makes sense to invest a lot.

1st test results:40km/hHC 198CO 4.92NO 211

Curb IdleHC 361CO 3.8

The following was done before the 2d test:

• Replaced catalytic convertor (reused the O2 sensor there, according to mechanic, it was ok) • Cleaned throttle body• Replaced air filter• Replaced fuel filter• Changed oil and filter• Changed spark plugs

2d Test results:

40km/hHC 185CO 5.25NO 98

Curb IdleHC 217CO 3.38

[allensteiner]

i don't know what the test results should be, it may vary state to state (?). but for fixes the ks can be bypassed with a 470k ohm resistor - checkout my ks bypass thread - the cooland temp sensor is cheap and replacing the o2's will make your car run better - mpg/power - those are more expensive but worth it in the long run - cheaper if you do them yourself. and your emissions are probably due to your o2's...i would think.

[maxhopper]

...and your emissions are probably due to your o2's...i would think.

My thought as well. When the O2 fails, it goes to a default mode that runs the fuel mixture rich.

[Q45tech]

When you bypass the KS with a 550k resistor the circuitry no longer hears the engine background noise and signals ecu to switch to emergency regular fuel program.

This will reduce engine power and increase fuel consumption at cruise a small amount. Engine may be more sluggish but not as bad as a failed KS which really significantly reduces ignition advance.