What’s at fault, is it my computer module, a bad CAT, or a sensor?
So my pickup has a single straight pipe I keep getting a check engine light that turns on and off when it wants to one week it says bad O2 sensor the next it's something with my CATs (I can read these codes with my programmer) I have a video of it starting on a 40 degree morning and it sounds horrible. I've had people tell me it's my computer module? When it gets cold like in the teens it barely starts.
My car has 119000 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Hi there. The codes would be helpful and don’t clear them. A sticking O2 sensor can cause drivability issues and set the Check Engine Light. If there is a catalytic converter code, I would focus first on the O2 sensor code and get that corrected and monitor the catalytic converter code to see if it returns. If it returns, then proceed with further diagnosis of the converter code. The ECM being faulty is a possible cause, but without proper inspection I would not recommend replacement.
Starting with diagnosing and correcting the codes is the best route to see if what is setting the codes is also causing the cold start issues. I strongly suggest acquiring a qualified technician to perform an inspection to avoid replacing unnecessary parts. YourMechanic has several available technicians that can assist you with a Check Engine Light inspection at your own location.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
The catalytic converter converts harmful byproducts of internal combustion to less-harmful compounds. If there`s an exhaust leak letting gasses out of the system before it reaches the converter, if the converter becomes damaged or if it`s missing altogether, the check engine light will activate in your dashboard.
Driving with A Failed Catalytic Converter
If you`re noticing slow powertrain performance, reduced acceleration, a smell of rotten eggs or sulfur from the exhaust, dark exhaust smoke, or extreme heat from under the vehicle, these are symptoms of a clogged Catalytic Converter, and it should be replaced quickly.
A failing catalytic converter is a common cause of check engine lights turning on, and it can lead to a decrease in fuel economy and engine performance.
A bad catalytic converter will lead to incomplete combustion within the firing cylinders causing an engine misfire and making it challenging for your car to start. Any time you notice frequent engine misfires, you`re experiencing the signs of a bad catalytic converter that needs a replacement.
A common emissions code seen in the field, a P0420 trouble code indicates that the catalytic converter isn`t functioning efficiently. To work at peak efficiency, the emissions or feed gases entering the catalytic converter need to be perfectly balanced and not excessively elevated.
The most common cause of a P0420 code is a faulty catalytic converter. The following are some other potential causes: Exhaust manifold damage or leakage. Exhaust pipe damage or leakage.
Incorrect air/fuel mixture, incorrect timing, or misfiring spark plugs could lead to a catalytic converter failure or worse. Spark plugs that don`t fire or misfire forces unburned fuel into the exhaust system.
It`s important to say that Cataclean cannot repair a part that has failed due to an excessive buildup of carbon. If the check-engine light stays on even after use of Cataclean, for example, then it`s possible that the damage to the catalytic converter is irreversible.
Most Common Check-Engine Light Repairs
For the fourth year in a row, CarMD found the vehicle`s catalytic converter is the most common check-engine light repair — and at $1,313, it`s also the priciest.
Yes, it is usually alright to continue driving in the short term with P0420. It does not pose a risk to the driver. Driving long term with this code can damage your engine and exhaust system. You don`t need to call a tow truck if you see this code, but you should try to diagnose and fix the problem as soon as you can.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
I have a bad oxygen sensor, bad power steering sensor, and a bad cam shaft sensor? Should I replace any of them?
ANSWER : When you say you have three bad sensors I can only assume you have had them tested and the end result is three bad sensors. If they tested bad then they should be replaced. The power steering sensor senses the load of the steering on the engine so it can raise the idle during parking maneuvers. The O2 sensor is used for fuel control and it may effect engine power and fuel mileage. The camshaft sensor cay cause no starts, engine running problems and all three will turn on the check engine light.
What’s at fault, is it my computer module, a bad CAT, or a sensor?
ANSWER : Hi there. The codes would be helpful and don’t clear them. A sticking O2 sensor can cause drivability issues and set the Check Engine Light. If there is a catalytic converter code, I would focus first on the O2 sensor code and get that corrected and monitor the catalytic converter code to see if it returns. If it returns, then proceed with further diagnosis of the converter code. The ECM being faulty is a possible cause, but without proper inspection I would not recommend replacement.
Starting with diagnosing and correcting the codes is the best route to see if what is setting the codes is also causing the cold start issues. I strongly suggest acquiring a qualified technician to perform an inspection to avoid replacing unnecessary parts. YourMechanic has several available technicians that can assist you with a Check Engine Light inspection at your own location.
Diagnostic code read o2 sensor bad, replaced o2 sensor, cleared code but engine light came back on, is it caused by bad air filter
ANSWER : Hello there. Typically jump starting a vehicle doesn’t trigger an OBD-II error code. However, one of the most common misdiagnosis issues with the P-2270 is replacing the O2 sensor before diagnosing if there are any exhaust leaks. Obviously, you’ll want to check for the exhaust leaks first, repair the damaged component, and then clear the codes before scanning the vehicle again. Sometimes the electrical harness attached to the O2 sensor is damaged or dirty which will also trigger this error code. The noise and vibration may be an indicator of a loose exhaust pipe, which may be the source of the error code staying on. If you need any help, have a technician from YourMechanic come to your home or office to diagnose your Check Engine Light and make the necessary repairs.
transmission control module failing. We just replaced the computer module (pcm) 4 days ago?
ANSWER : The P0700 trouble code is a code for transmission control module (TCM) failure. Without knowing the other codes, it will not be possible to give you an accurate answer; it all depends on the other codes:
If you get a P0755 code, you may have a transmission solenoid pack issue.
P0725 indicates a likely crank position sensor issue.
I would suggest having your Check Engine Light diagnosed by a qualified mechanic.
My code reader says I have a bad mass air flow sensor ans crank shat sensor test drive ran better shut off & engine Lt. Same code
ANSWER : Hi there. The problem you are describing, sounds like you may have a poor connection in the connector at the mass airflow sensor. Although, sometimes aftermarket parts do not perform as well as factory (OEM) parts. Check for corrosion and/or wide spacing in the terminal ends. Compare the terminal ends in the connector using a flashlight to see better. The terminals can be tightened. If you are not comfortable with doing that, a replacement pigtail (connector) is available. You vehicle may require further diagnosis performed with a scanner that provides parameters that can be viewed as the fault occurs. If that is the case, I recommend having your vehicle’s electrical circuits inspected in order to pinpoint the underlying fault.
Bad camshaft position sensor?
ANSWER : Hi there. You might find reading this article very helpful in trying to diagnose your P0016 OBD-II trouble code issue. It explains common causes, symptoms and solutions.
How do I test which camshaft sensor is bad? My Check Engine Light is on and the scanner says a bad camshaft sensor is at fault.
ANSWER : There is only one cam position sensor on this engine, located just in front of the oil filler cap.
Testing camshaft/crankshaft sensor failures, unfortunately, often only has 2 options for testing a suspect component:
Replace it with a known working part to see if it solves the problem.
Get out your oscilloscope and start looking at wave patterns.
Simple "resistance" testing with an ohm meter while not running will only predict a completely failed sensor with which the car would not run.
If you need help with this, have your camshaft sensor and Check Engine Light inspected further by a certified technician such as one from YourMechanic to confirm this diagnosis, get an accurate assessment of damage and cost estimate for repairs. YourMechanic can dispatch a mobile, professional mechanic to your location for this repair.
I did replace the heater core and two sensor the crank sensor and camshaft sensor it didn’t work can it be the computer
ANSWER : If the check engine light is on, what kind of codes is the system detecting? Do you have spark at the plugs? If you have spark, does spritzing some starter fluid give you a momentary startup? If so, there is a fuel issue. More symptoms and information on the car’s behavior before and after the parts you replaced would be very helpful. At this point, I would recommend an inspection from YourMechanic.com to diagnose this car starting problem, get an accurate assessment of damage and cost estimate for repairs. YourMechanic.com can dispatch a mobile, professional mechanic to your location to help you get your car up and working again.
