Why did my car shake and the check engine light flash while stopped at a light?
What you experienced was almost certainly a misfire event and the cause may be recorded as a diagnostic trouble code (DTC) in the engine controller’s memory. Most failures that are significant enough to cause MIL illumination will record a trouble code and its environmental/ data information from the moment, even if the MIL is no longer lit. Onboard Diagnostics work constantly to keep the MIL off, looking for a reason to turn the CE light out if the condition hasn’t been seen again recently, eventually even erasing trouble codes if all’s good. I can only speculate on the nature of your event, but a thorough scan to retrieve codes and freeze frame data of the moment will often shed some light on the situation.Misfires come in many flavors, ranging from slight loss of performance in a single cylinder, to one or more holes being completely dead. Your description of shake at an idle implies a power imbalance, which usually involves complete loss of performance, but just one hole.Barring an at-home scanner being available, rolling the ignition key from LOCK to RUN three times, then leaving it in the RUN position at the end will initiate the customer code-read feature, spilling any matured codes stored in the PCM through the instrument cluster’s odometer window. All codes will be four digits in length, beginning with the letter P, such as P0123. DTC information can be found at OBD2-OBDII Engine Light Trouble Codes Definitions, Description and Repair Information online.One-trip failures - those that have not quite matured - will not be displayed in this feature, but will show up on a high-end scanner if present.If only a single cylinder misfire code is retrieved, pull the coil and spark plug to inspect for signs of flashover - black marks on the upper spark plug insulator and inner coil boot that will not scratch off with a fingernail. Flashover is pretty common on coil-on-plug ignition systems and the cure is to replace both the boot and spark plug together. Worn plugs tend to incite this sort of situation as spark will always seek the path of least resistance.If your DTC list includes an injector control circuit code that matches the cylinder of misfire, chances are good that the injector is at fault. The injector may test as completely normal when cooler, but will go to an open circuit once heated, either naturally or with a heat gun.
Will a bad O2 sensor cause a cylinder 2 misfire?
It’s possible, not probable, a bad o2 sensor changes the fuel to air ratio, it should affect all bank cylinders equally, however a weak coil or worn plug may be more sensitive to the change and rich running may have fouled the number two plug, another possibility is that the o2 sensor is good and reading an incorrect ratio due to the bad plug, I had a lean code once caused by bad plugs, the computer compensated for extra fuel by leaning the mixture and then throwing a lean code followed by a misfire code, new plugs fixed both issues.
What are the symptoms of a bad transmission speed sensor?
On some vehicles, there are sensors that function specifically for certain parts of the vehicle. Sometimes a bad speed sensor will mess up the function of the ABS brakes (causing them to overreact or not kick in at all, which usually creates a light on the dash), other times it can cause erratic speedometer readings and/or (for auto transmissions) cause inconsistent shifts and it shifting completely out of gear into neutral at random. Some vehicles it will do all of these things at once, but you should get a CEL (check engine light) or ABS light to show up on the dash if one of these things are becoming problematic enough to cause issues.