Failed emissions after EGR code

STEPHANIE CHESTER

MEMBER
1996 TOYOTA TERCEL
1.5L
4 CYL
2WD
MANUAL
227,000 MILES

Check engine light was on and my code reader gave code P40. I cleaned out the EGR and the air seemed to be flowing through it. Cleared the code and went for a drive and the check engine light came back on. I took it to a mechanic for diagnostics and they said we need to replace the EGR Vacuum Solenoid. We replaced that part and the check engine light turned off but, it didn't pass emissions. The car failed HC PPM 2500 304.2 Idle 283.3 Limits 220.0. Any thoughts on my next course of action?

3 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Stephanie,

The HC PPM is extremely high. That usually indicates unburned fuel. Have you checked fuel pressure? The regulator may be causing pressure to be too high. Also, a faulty engine coolant temp can cause the air fuel mixture to be off. There are other things such as a faulty intake air temp sensor, a leaking injector and so on.

Does it have a rough idle? Have you ever noticed black smoke from the exhaust?

Tell me. Do you have a live data scanner? If you do, can you tell me the short term fuel trims (STFT)? Also, can you confirm the engine coolant temperature sensor is reading properly?

You listed above code P40. The code should be a P and then 4 numbers. Let me know if you remember what it was.

Keep in mind, this could even be a plugged air filter. I attached a pic below indicating what can cause high hydrocarbon (HC) readings. Take a look through it.

Let me know if any of those things have been checked and if any different codes have been present.

Joe

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Friday, May 29th, 2020 AT 7:33 PM

STEPHANIE CHESTER

MEMBER
2 POSTS

Thank you Jacob B for your response to my question. Sorry for my typo, the code was P0401. The car seems to run well, and it idles smoothly. When my guy bought it, I saw a cloud of gray smoke from the tail pipe but it really doesn’t seem to smoke a lot. I don’t have another scanner, just the one for the codes.

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Saturday, May 30th, 2020 AT 9:42 AM

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

That code makes sense. That one is related to the EGR. Since the vehicle is running properly, I need to know live data information to help determine why the hydrocarbons are so high. As I mentioned, it is usually due to excessive unburned fuel. Is it possible for you to get your hands on one?

Joe

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Saturday, May 30th, 2020 AT 8:20 PM