"Check Engine Light" Only When Its Warm?

[germanxmascooki]

Hi everyone,

So my "Check Engine Light" only goes on when its warm outside. If it's cold (like 30 or 40 degrees), it stays off. Any ideas?

I'm kinda a newbie to cars, but it's a stick shift 2002 Acura RSX. I bought it used, and there's quite a bit of rust on the engine mounts & brackets (Maybe the electrical wiring?). I just changed the air filter. Autozone's code reader said "Gas Mixture Too Rich or Lean", "Electrical Wiring Problem" or "Malfunctioning O2 Sensor".

The mechanic told me to replace every bracket, mount & wire in the engine!!
(Oh, I've noticed that it's a bit jerky at low RPMs, like below 2.5k. Not sluggish, but a little jerky.) I have no idea what's going on? Any wisdom would be super-appreciated!

 

[vshah]

i'm almost entirely clueless but it sounds like something to do with the air flow or air temperature sensors in the intake

 

[SearchMaster]

What's the code exactly? Have you googled "acura rsx" and "pxxxx", whatever the code is, to see if it's a common problem and what the resolution might be?

 

[ssblood]

Mixture to rich or lean would be a by product of the bad o2 sensor. When the car is cold the engine is running in open loop mode and not using the o2 sensor. When it gets to operating temperature it uses the o2 sensor to manage the air/fuel ratio. Bad o2 = mixture to rich or lean. Electrical problem could be the heater bad in the o2 sensor or an entirely seperate problem. What bank and what posistion o2 sensor? Basically you've got a bad o2 sensor, the specific code will tell you which one.

 

[guyver01]

make sure your gas cap is properly tightened..

 

[Vette73]

I would replace the O2 sensor forst. It is a maintaince item anyways so chances are its due. Also replace the PCV valve. Its cheap and easy to get to.

Replace those 2 things first and then disconnect/reconnect the battery and drive normal for a day.

Also you don't have a K&N filter (or other "high flow" intake/filter) do you? If so add clean MAF sensor to the list.

 

[SuperSix]

I would replace the O2 sensor forst. It is a maintaince item anyways so chances are its due. Also replace the PCV valve. Its cheap and easy to get to.

Replace those 2 things first and then disconnect/reconnect the battery and drive normal for a day.

Also you don't have a K&N filter (or other "high flow" intake/filter) do you? If so add clean MAF sensor to the list.

This. In the future - record the "PXXX" engine code when you get them checked - easier to diagnose with the exact code.

It sounds like a simple o2 sensor failure. If you decide to replace them yourself - and based on what I can glean from your post in regards to your mechanical abilities - buy the special socket for o2 sensor replacement. Don't be a moron like my friend and wipe off the anti-seize compound that should come on the threads of the replacement sensor. Denso or Bosch should be fine as replacements.

 

[Castiel]

Solid Light = Emission Code
Blinking Light - Miss fire

 

[SuperSix]

Solid Light = Emission Code
Blinking Light - Miss fire

What? The CES light?

 

[Vette73]

Solid Light = Emission Code
Blinking Light - Miss fire

Not in most cars, at least in the US. If you are talking about the engine light.

 

[LTC8K6]

Not in most cars, at least in the US. If you are talking about the engine light.

Yes, in the US. 2008 Fusion manual, for example:

Solid illumination after the engine is started indicates the On Board
Diagnostics System (OBD-II) has detected a malfunction. Refer to On
board diagnostics (OBD-II) in the Maintenance and Specifications
chapter. If the light is blinking, engine misfire is occurring which could
damage your catalytic converter. Drive in a moderate fashion (avoid
heavy acceleration and deceleration) and have your vehicle serviced
immediately by your authorized dealer.

2004 CTS Manual:

• Light Flashing—A misfire condition has been
detected. A misfire increases vehicle emissions and
may damage the emission control system
on your vehicle. Diagnosis and service may be
required.
• Light On Steady —An emission control system
malfunction has been detected on your vehicle.
Diagnosis and service may be required.

 

[cheezmunky]

Yes, in the US. 2008 Fusion manual, for example:



2004 CTS Manual:

My last car (Subaru) had a solid light with an engine misfire code. Solid light meant take it in to have it looked at asap. Blinking light meant don't drive it at all.

 

[TheHashmaster]

most likely a bad oxygen sensor, as it is a maintenance item and is responsible for telling the engine computer to adjust the air/fuel ratio, all u have to do is find out which sensor it is, pre or post catalytic converter

 

[LTC8K6]

My last car (Subaru) had a solid light with an engine misfire code. Solid light meant take it in to have it looked at asap. Blinking light meant don't drive it at all.

OBD2 is pretty much OBD2...