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Indicator Light and starting problem

I have a 96 Toyota Camry V6 with 170K miles. Up until the last few months, it has only needed regular maintenance. In January, the catalytic converter was replaced and then in May the air conditioner compressor was replaced. A couple of weeks after the compressor was replaced, an indicator light came on while driving…the one that says there is an electrical problem in the engine or transmission…or your gas cap is loose. There was no change in how the car ran. The mechanic put it on the computer and could not get any codes. He thought possibly he didn’t reset something when doing the converter. He reset and turned out the light. It came on again about three weeks later and I ignored it for 2 weeks. The car didn’t start one morning. I don’t think I’d left any lights on or doors open. Again, there are no codes coming up and tests of the battery say it is fine.

My mechanic is very thorough and usually puzzles out issues (we had a Sable before this that lasted as long as it did partly due to his diligence). This one has him stumped.

Any ideas?

You did not give us any real details about this car’s maintenance history. Just as an example of what can happen with deferred maintenance, failure to replace spark plugs and to do other types of maintenance can cause a catalytic converter to go bad.

Following this scenario to the next step, overdue maintenance can also cause other problems, such as inability to start the engine. What “regular maintenance” has it had, and how regular has it been?

The car has been maintained. The oil is changed every 6 months, and with the current driving history, is about every 4K miles. This is done by the same mechanic, so he can check fluids, belts, etc. It has also only been owned by us and garaged for thirteen years. The last tune up includes platinum spark plugs and we follow any all maintenance suggestions. The timing belt was replaced at about 95K miles. The brakes are checked with every oil change starting a year after they are done. This is probably the reason it has lasted for over 13 years and never been unreliable in anyway until this issue arose.

When you say the ‘car didn’t start…’, do you mean the engine didn’t crank or do you mean the engine cranked but did not catch and run?

Your mechanic has good reason to be puzzled as a correctly operating PCM stores a code when they turn on the Check Engine Light. I am wondering if he should try to set a code on purpose, by leaving the gas cap loose for example, and seeing if the scanner reads the resulting code. Also ask him if he can communicate with the PCM as he should be able to get freeze frame data. I am wondering if the problem could be a faulty PCM although a faulty PCM will usually not set the CEL.

Post back when you get this problem solved.

The way it is supposed to work is that the computer detects emissions related problems, stores a code indicating what problem(s) it found and turns on the Check Engine Light. In some cases, if the condition that causes the problem isn’t seen on subsequent starts or “drive cycles” (don’t ask), the codes will be cleared. The CEL is supposed to be cleared if the code is cleared.

All this stuff called OBD2 was first required in 1996 and some vehicle computers had troubles in the early years. It sounds like yours might be one of them. You might ask in the appropriate forum at and see if anyone there knows of a specific problem with 96 Camrys that might leave you with a CEL lit and no codes.

Longer term, you might consider buying a cheap code reader – $60-80 at Autozone, etc – and getting your mechanic to show you how to use it. Use it to to turn out the CEL and the next time the light comes on, use the code reader to read the codes before you turn the engine off. Hopefully, that will catch the elusive problem code. $60-80 isn’t that much compared to the aggravation and cost of a mechanic’s visit and the exasperation of finding that there is no code stored. You’ll possibly be able to use the reader on your next car as well. The last time I looked, it appeared that the OBDIII specification seemed to be stuck in a preliminary phase, and modern code readers are purportedly CAN (Controller Area Network) compatible at least as far as reading OBDII emissions codes goes – which means they should be able to read the codes on any vehicle sold in the US (or Canada?) since 1996.

I tried to turn on the engine and got clicks. The AAA tow person turned off the ancillaries (air conditioner, etc.) and got it to turn over and start. (Honestly, I’m embarassed I didn’t think of that. My only excuse may be that I was late for an appointment and that it’s been many years since we’ve had a car that had problems) The engine sounded very weak, but got the battery charged enough to drive it to the garage.

The engine solenoid just clicking during a start attempt is an ELECTRICAL problem. Fix that before tackling another problem.
Full battery voltage isn’t getting to the starter solenoid. Clean the battery cable terminals (removed from posts) with files, knife, or sandpaper. There may be a small cable bolted to the battery terminal. Make sure that smaller cable connection is tight.
Also, the power to the starter solenoid goes through the 1. ignition switch, 2. the neutral safety switch, 3. and, maybe, a starter relay. Any one, or all, of these could cause the voltage to drop too much to energize the starter solenoid.

It turns out that this time (second time the light came on) that there was a code for low emissions pressure. The first time there was no code and when I asked about the 02 sensor as a possibility this time, there was no code for that…and I mistakenly took that for no code at all.

Is there anyway to determine if there is a defect in the part put in the car in January which was the “front part” of the emission system in the Camry, including the catalytic converter?


Stay on track. Get the car to start consistently; then, you can drive the car until the check engine light comes on, have your mechanic read the code, and let us have the codes for interpretation. Sound like a plan?

Has anyone tested the charging system?
How old is the battery?

Your description of the visit by the AAA guy and the results of his visit combined with your description of what happens when you turn the key all point pretty clearly to either a bad connection, a weak battery, or a bad alternator/regulator (same assembly).

I suspect that the battery charge warning indicator is turning on and not the check engine light. Have the alternator and battery checked along with the wiring to them.

Thanks. The mechanic thoroughly checked the battery and connections. He can not get the car to repeat the problem. I have the car back. He did not charge me and asked if it happens again to call him and he will come over so he can observe the problem. It is somewhat a risk, except I tend to drive only locally.

Thanks. Great plan…as long as I don’t get stranded somewhere.

The car has been running fine. There has not been a repeat of the starting issue.

The CEL came back on. The code is PO420 (I discovered that Autozone will read codes for free as long as your car has an OBDII sensor accessible inside the car. The Camry 96 hides it behind the accessory cup).

Is it possible the catalytic convertor put in the car in January is defective or could there be another problem with the emission system? The car won’t pass inspection (in a couple of months) with this problem.