SES Light and then Oil Prrssure and Battery Light?

First, let me start off by explaining a couple things. Back around January and February I had set an SES Light. I had two codes. One was P1811 and the other was P0171. I installed a shift kit pretty much as a band-aid for the P1811 code. For the P0171 code, I honestly didn't do anything for a little while because I was at wits end trying to find the vacuum leak but I never could find it. I have replaced the LIM gaskets so I don't believe those are the problems. It seemed like it was just the next day and my SES Light randomly turned off. "Cool", I thought. This is the way I've been driving my car all year without any problems until yesterday.

After filling up with gas (93 octane), I started my journey home like normal. Everything was as normal as my car could be. Then, about one mile from home, my SES Light came on. I pull into my driveway and as I'm about to pull into my spot, I lose power steering. I then lose all braking and at this point the engine isn't running. I'm able to get the car stopped, thankfully. I put it in "Park", turn the key "Off", and it fires right back up. I continue to pull into my spot, go into reverse, go back to "Drive" and it stops running again. WTF! Now, while all of this was happening, my oil pressure light and my battery light both turned on. In the past I've had the battery terminal wires work themselves loose so I checked those first and they were tight.

Fast forward a few hours later and I go to start my car and it starts, but it hesitated for a split second. It was running as normal as could be, but the SES Light was on and stayed on. The oil pressure light and the battery light had turned off. Weird. Obviously my next step is to get the code(s) read, but I wanted to see if anyone had any initial suggestions. Any reason as to why the oil pressure and battery light turned on? I was thinking they just turned on because of the engine stopping but the key in the "On" position. Sorry for the long, drawn out explanation, but I like to get things settled first and go from there.

When the engine quits running in the run position, you lose oil pressure and the alternator stops turning. You get an oil pressure light and a charge light. Nothing unusual about that at all, any car would do that. My first check would be fuel pressure. Maybe your fuel pump is going or gone.

LARRY70GS wrote:

When the engine quits running in the run position, you lose oil pressure and the alternator stops turning.  You get an oil pressure light and a charge light.  Nothing unusual about that at all, any car would do that.  My first check would be fuel pressure.  Maybe your fuel pump is going or gone.

That's what I was thinking about the oil pressure and battery light, but I just wasn't sure. The fuel pump is definitely a possibility. Although, I really hope that isn't the problem.

Going to AutoZone to have the code(s) read and have the battery and maybe alternator tested.

A simple fuel pressure tester will tell you if you are losing fuel pressure. There is likely nothing wrong with your alternator or battery. With the engine running, a voltmeter across the battery should read around 14.3-14.5 volts.

Took it to O'Reillys instead of AutoZone and surprisingly there was a code for the TPS. I guess if I think about it that makes sense because it was only stalling at low speeds without any throttle input. I didn't even think about a sensor like that because I only experienced the symptoms twice before driving to O'Reillys today. It stalled five times there and back.

Time to revisit this for a little while. I've since replaced the mass air flow sensor with a new one and had the codes cleared. Everything has ran perfectly fine since then. This morning out of the blue, the SES light turns on while cruising and now my 1-2 shifts are shifting at 3K versus at 2K where they would normally be at with the driving I'm doing. The thing is, the car won't stall at low speeds, or at least it hasn't yet. I've always had the delayed shifting when the SES light has randomly turned on, but never just delayed shifting and no stalling. Its always been both. Any thoughts? Hopefully what I'm saying makes sense.

My Lesabre T-type, with it's old engine would do something very similar when the TPS needed adjusted. Random SES light and it stalled once.

I had a 2000 SSEi that the TPS went bad and it would randomly stall OR idling really high. What exactly was the code for the TPS if you remember?

A bad TPS will certainly change your shift points because it thinks the throttle is at a different position than it really is.

I got the code read and it was P0121. I took a look at some vacuum lines just to see if maybe something came apart, and sure enough one was broken. The funny thing is though, today on my way home from work, my SES light turned off even though I know there's a vacuum leak. I don't know what's up with that, but I ordered a vacuum hose kit that I'll be installing whenever it arrives.

As long as you are at it, check the *wiring* to those sensors for breaks inside the insulation. Once in a while you'll find an issue with embrittlement of the copper wires, they can break inside the insulation at the crimp to the connector pins. While you are looking at the sensors, it's a great time to wiggle the wires gently to check for breaks in the conductors inside the insulation. You may need a meter - what you will see is when you clip the meter leads across the connector then wiggle the wire the resistance fluctuates wildly.

Why did you replace the MAF sensor after a code for TPS was scanned?

When you fix the vac leak, see if you get another TPS code. If so, test/replace that sensor.

AA wrote:

Why did you replace the MAF sensor after a code for TPS was scanned?

When you fix the vac leak, see if you get another TPS code. If so, test/replace that sensor.

I had two codes before, one for the MAF and one for the TPS. I replaced both sensors, but the code for the TPS remained. After just the TPS code remained is when I found the broken vacuum line.

What I don't understand is that in the morning for example, my SES light will be on. I'm assuming (and hoping) It's for the broken vacuum line. In the afternoon, 9 hours later, the SES light will sometimes turn off, even though the vacuum line is still broken.

It's probably because symptoms with vac leaks are not always consistent, and depending on length of your trip, and driving conditions, will trip the SES. But most SES are programmed to turn off after a trip or two without triggering, so the light will go out until the conditions are met again. Your experience is typical for a problem related to vacuum or some other unspecific cause. Spark issues are similar, and may never throw codes. Something very specific like a bad O2 or voltage regulator will throw SES much more consistently, and the lamp will stay on.

Whenever the lamp is on constantly, it's more likely that the code is specific and related to a specific component. When SES is off/on, and multiple codes are read, it's more likely an indirect issue causing multiple symptoms. Less likely electrical, more likely vacuum, mechanical, fuel or spark.