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I've been working on a code 32 SES light for awhile on my '87 Vert. I have an FSM. It seems the SES light only come on after an extended cruise at 65 mph when certain conditions are met. At low speeds around town I don't get a light. I first tested the EGR valve and it wasn't holding when applying vacuum to the valve when cold. I bought a new one and replaced it. Road test, code 32. I had a new spare EGR solenoid so I figure why not just replace it. Since I have an '87 the solenoid is under the plenum by the thermostat housing. Thought I could just remove the housing bolt and install the new solenoid...NOT. I started the engine and had a coolant leak. Ok, I moved the throttle body aside, removed and replaced the thermostat housing and gasket and installed the new egr solenoid. I checked the vacuum hoses and repaired some brittle lines with rubber vacuum hoses. Road test...code 32. Really? Ok, better look at the FSM. I test the solenoid per the FSM and the solenoid is not holding vacuum when I initiate a diagnostic test. It's brand new and defective. I've had it for a long time and don't recall where it came from but it didn't look like it was ever installed. So I test my old solenoid and it tests good. So I figure don't remove the thermostat bolt and just jerry-rig the old solenoid back in. Road test, code 32. So what I learned is during certain driving conditions the ECM commands the EGR solenoid to meter the vacuum to the EGR valve to recirculate some exhaust gas into the intake manifold to burn. Since I have an '87 there is an external EGR pipe between the exhaust and the intake manifold with the EGR temp switch. As hot gas passes through the pipe when the EGR valve is operating the EGR temp switch heats up and the switch grounds a wire from the ecm. If the ecm sees no ground on this circuit when certain driving conditions are met then the SES light goes on with code 32. So I checked the integrity of the vacuum lines, and the electrical connections to the egr solenoid and the egr temp switch and they are good. So I read that the EGR temp switch, if grounded during startup, will set a code 32 immediately. Since my car initiates the code 32 after some driving I ruled out the switch being grounded during startup. However, the switch is supposed to ground when heated. So I ran a jumper wire from the EGR temp switch bare terminal and ran it inside the car. I drove the car until the SES light came on as code 32. I immediately grounded the jumper wire and the SES light turned off. I also read that if the state of the EGR temp switch changes, in this case grounded, then the SES light should go off. So I confirmed this. This doesn't mean that the EGR valve and the EGR solenoid and the associated circuit is working properly but after replacing the EGR valve, tested that it works, tested the EGR solenoid and it works, the wiring and vacuum lines are intact, I'm thinking that the EGR temp switch is bad. I removed it and during bench testing realized that the wire terminal and sensor are very loose in the temp switch housing. If I screw the sensor and wire further into the housing it will ground. But since this switch works on a bi-metal principle it need not be grounded by screwing in the sensor too far. Even when I back it out about a turn the ceramic insulator is loose and I can move it and get a ground intermittently. I'm thinking of simply replacing this $65 switch to see if the code 32 goes away. I borrowed my friends scanner to try to retrieve live data but the screen is too hard to read during testing. I don't like throwing parts at the car but it seems to, in my mind, be a bad EGR temp switch even though I can't confirm that EGR gases are passing through the EGR temp switch external pipe. I can just throw another $65 at the car in hopes the code goes away or spent countless hours trying to scan live data with a scanner which I don't have. Sorry for the long post, just venting a little and sharing what I've learned about code 32. One other interesting thing I learned was there was a technical service bulletin, TSB, issued for an erroneous code 32. The TSB directed technitions to inspect the TCC solenoid, torque convertor trans solenoid, for a failure or short. The EGR solenoid and the TCC solenoid are fused by the same fuse in addition to a bunch of other circuits. It also mentioned that if the torque convertor lockup is working then it's probably not the cause of the erroneous code 32. Anyway, more to follow once I get the new switch in.
Last edited by MrRenoman; Mar 27, 2025 at 12:41 PM.
Oh, one other thing I forgot to mention. The FSM directs to check to make sure the vehicle has a minimum of 7" of ported vac, intact vacuum lines, and intact wiring. At some point, and I believe it was after I put in the new EGR valve, I tested the ported vac fitting under the throttle body and discovered there was no ported vac. It seemed like the points of failure were adding up. So I unbolted the throttle body and on the back I could see how the ported vacuum fitting is installed and that the throttle body casting has a path from the bottom of the throttle body to the top. So I removed the BBK 52mm id plate off the top of the throttle body and discovered that the gasket was installed 180 degrees off and the ported vacuum path and port were not sealed from the atmosphere. Well I'll be. So I rotated the gasket, re-assembled, and tested the ported vac. Sure enough, I was getting almost 10" of ported vac. Couple this with the bad EGR valve, a bad new EGR solenoid, vacuum leaks, and I forgot to mentioned a deteriorated EGR solenoid connector, and what seems to be a bad EGR temp switch, I'm batting 1000. Every conceivable failure in this system has been thrown my way. No wonder this code is hard to diagnose and fix.
lt sounds like you have had or checked the methods of failure.
In my case, I had an '88 with the code 32. I replaced the EGR valve. Still code 32. I took it off and found it was bad. I went back to the parts store and they gave me a new one. It was bad also. I got a third and it was the wrong part. I got my money back and went to a different store. I got one that held vacuum and worked. No more code 32.
I can appreciate the code 32 hassles. I would double check that the EGR is actually good.
Hi, thanks for your reply. I checked my new EGR valve after I received it to make sure it opened under vacuum and didn’t bleed down. I’m thinking the EGR valve is good. It’s an AC Delco 214-5535.
Originally Posted by QCVette
lt sounds like you have had or checked the methods of failure.
In my case, I had an '88 with the code 32. I replaced the EGR valve. Still code 32. I took it off and found it was bad. I went back to the parts store and they gave me a new one. It was bad also. I got a third and it was the wrong part. I got my money back and went to a different store. I got one that held vacuum and worked. No more code 32.
I can appreciate the code 32 hassles. I would double check that the EGR is actually good.
fighting the same thing here. Tested everything according to FSM and still get the occasional check engine light / code 32. Actually thinking of a custom chip (for other things) and include code to not log 32s
I share the frustration. I'm really trying to figure out what's going on. Documenting and sharing my results may trigger someone who has figured it out to share. I'm hoping, just like all the other things I've done will fix it. It seemed like every part or functionality of the EGR system had a failure and each time I discovered a failure I thought that fixing or replacing the affected area would have fixed it. Same thing with the EGR temp switch. No guarantee it will fix it but still think it will. Go figure. I want to feel positive about replacing this part but will be at my wits end if it doesn't fix it.
Originally Posted by dburgjohn
fighting the same thing here. Tested everything according to FSM and still get the occasional check engine light / code 32. Actually thinking of a custom chip (for other things) and include code to not log 32s
Oddly enough, my SES light came on yesterday, both on the way to and on the way from and appointment. Also a code 32.
I replaced my EGR valve a while back and hadn't seen the SES light nor the code since, and any bad vacuum hoses were also replaced at the same time.
So I dunno.
I dumped some Seafoam into the crank case and also sprayed a can of it through the intake in the Fall. Also dumped two cans of Seafoam in a full tank of 93 octane. I hadn't really driven it since winter set in.
I drove maybe 200 miles on the seafoam in the crank case before changing that oil. Still on the same tank of fuel, then boom...SES light and code 32.
But I was free from the SES light and the code 32 for quite some time after replacing the valve and the bad vacuum hoses initially.
I did order a new EGR temp sensor from Keen Auto Parts. After inspecting my existing switch and finding the ceramic insert loose to the metal housing I decided to epoxy the ceramic to the housing. I used a semi-fast setting 2 part epoxy to keep the ceramic from moving around. I think that if I get the pintle end of the sensor screwed in so the tip is just short of bottoming out then it may fix the switch by stabilizing the bi-metal screw in place so when the heat causes it to move to the ground then it might just work. I always try to fix my parts and in the process learn something new. If this fixes it then I might just keep the new switch in case I need it since I have a TPI engine in my El Camino but the EGR temp sensor is attached to the EGR valve under the plenum. Anyway, I'm going to give this a try.
Last edited by MrRenoman; Mar 26, 2025 at 03:12 PM.
To adjust the Temp Switch: Connect your VOM on Ohms between the wire and the case. Turn the 'screw' inwards until the VOM shows continuity, then retract the screw 1/8 turn. Secure the screw.
If the switch is detected closed upon start-up, you get an instant SES and Code 32. You can't adjust it by "feel". Use your VOM.
HALLELUJAH!!! NO CHECK ENGINE LIGHT!!! I just drove the car about 70 miles and where I'd usually see the SES light come on, it didn't. As mentioned in my previous post #8 I worked on the EGR temp switch. Basically, the EGR temp switch consists of 3 major parts. The body, which has the threaded portion that screws into the crossover pipe, a ceramic insert, and the temp switch, let's call it a pintle, that screws into the threaded portion of the ceramic insert. I noticed during inspecting the switch that the pintle threads are loose in the ceramic insert, and the ceramic insert is loose in the body. While bench testing I observed that when I bottom the pintle into the ceramic insert so the end of the pintle touches the body then I get continuity from the electrical wire to the body, which is supposed to occur when the switch gets hot. I backed out the pintle about 1/2 turn so the circuit is open. However, when I rock the pintle in a sideway motion I notice that the pintle is loose in the ceramic insert and the ceramic insert is loose in the body. When I rock the pintle it grounds out intermittently. As mentioned in my previous post I epoxied the ceramic insert to the body, then added teflon tape on only the threaded portion of the pintle. Upon re-assembly, the pintle was tight in the ceramic body and the ceramic body was securely attached to the body with epoxy. I did order a new one so in case this didn't work I could replace it. But it seems to work fine. So to summarize...
I replaced my bad leaking EGR valve with a new one.
As per the FSM for Code 32..."Before using this chart, check vacuum hoses for leaks, restrictions and check for ported vacuum source to EGR solenoid should have at least 7" vacuum at 2000rpm.
The ported vacuum port is below the throttle body. I had a problem with the id plate gasket and had no ported vac. I fixed it by orienting the gasket correctly and re-assembled.
I replaced all the vacuum plastic tubing, where necessary, with 5/32" vacuum rubber hose. I even removed the rubber connector on the EGR vacuum solenoid to eliminate any leaks. I was able to just push the vacuum hose on the nipples.
If you look at the Emission Hose Routing diagram on the radiator shroud you will see that the same ported vacuum line that goes to the EGR solenoid and actuates the EGR valve also feeds the tank pressure control valve and the control valve on top of the carbon canister. Any failure or leaks in these valves or vacuum hoses going to these parts will reduce or prevent ported vac from operating the EGR system and the carbon canister system.
Per the FSM, the ported vacuum side of the EGR vacuum switch should hold vacuum when the car is put into diagnostic mode, shorting ALDL ports A&B, key on, engine off.
I discovered my new EGR solenoid was bad and put the old EGR solenoid back on since it tested good.
I tested my wiring to the EGR solenoid by putting the car in diagnostic mode and probing the unplugged connector with my voltmeter resulting in 12 VDC at the connector which is good.
I also tested the EGR temp switch wire by probing the terminal to ground with my voltmeter, key on, engine off and not in diagnostic mode. The voltmeter read 12VDC.
The only remaining part that was in question was the EGR temp switch which I tested and fixed. Attached are a few pics and comments.
I epoxied the ceramic insert to the body with 2 part epoxy. I wrapped just the threaded portion of the EGR temp switch pintle with teflon tape to keep it in the adjusted position which was about 1/2 turn from bottoming out.
Last edited by MrRenoman; Mar 29, 2025 at 01:14 PM.
Thanks, I did exactly as you posted. Although I did unscrew it about 1/2 turn. It seems to work.
Originally Posted by IHBD
To adjust the Temp Switch: Connect your VOM on Ohms between the wire and the case. Turn the 'screw' inwards until the VOM shows continuity, then retract the screw 1/8 turn. Secure the screw.
If the switch is detected closed upon start-up, you get an instant SES and Code 32. You can't adjust it by "feel". Use your VOM.
The easiest way I found out if my EGR temp switch was a possible cause was to run a jumper from the temp switch to inside the car. The top right opening of the ALDL connector is ground. So I had a terminal and wire that slid into the ground port and had the jumper wire from the temp switch at hand. When the SES light came on, I just connected the two wires together and shortly thereafter the SES light went out. Per some other information books I looked at "if the status of the EGR temp switch changes then the SES light should go out" In my case the status of the temp switch changed when I grounded the terminal. It's an easy test but it doesn't prove that the EGR valve, the EGR valve solenoid, and your electrical and vacuum lines are good. In my case I had tested, fixed and repaired every single possible trouble point which led me to believe the only remaining issue was the EGR temp switch. In a fully operating EGR system the only way the ecm knows the system is operating properly is if EGR prompted exhaust is routed through the EGR and on early C4s the temp switch is on the EGR valve or exhaust is passing through the external EGR temp switch tube on later C4s. I own an '87 with aluminum heads and the switch is on the external tube. Once that switch gets hot, it grounds, and the ecm picks up on that changed status and no check engine light will show. But if the switch is bad and can't ground out then you'll get an SES light. Also, if the switch is defective and grounded out when cold then the ecm will initiate a code 32 immediately or soon after startup.
Originally Posted by Natty C
Oddly enough, my SES light came on yesterday, both on the way to and on the way from and appointment. Also a code 32.
I replaced my EGR valve a while back and hadn't seen the SES light nor the code since, and any bad vacuum hoses were also replaced at the same time.
So I dunno.
I dumped some Seafoam into the crank case and also sprayed a can of it through the intake in the Fall. Also dumped two cans of Seafoam in a full tank of 93 octane. I hadn't really driven it since winter set in.
I drove maybe 200 miles on the seafoam in the crank case before changing that oil. Still on the same tank of fuel, then boom...SES light and code 32.
But I was free from the SES light and the code 32 for quite some time after replacing the valve and the bad vacuum hoses initially.
The easiest way I found out if my EGR temp switch was a possible cause was to run a jumper from the temp switch to inside the car. The top right opening of the ALDL connector is ground. So I had a terminal and wire that slid into the ground port and had the jumper wire from the temp switch at hand. When the SES light came on, I just connected the two wires together and shortly thereafter the SES light went out. Per some other information books I looked at "if the status of the EGR temp switch changes then the SES light should go out" In my case the status of the temp switch changed when I grounded the terminal. It's an easy test but it doesn't prove that the EGR valve, the EGR valve solenoid, and your electrical and vacuum lines are good. In my case I had tested, fixed and repaired every single possible trouble point which led me to believe the only remaining issue was the EGR temp switch. In a fully operating EGR system the only way the ecm knows the system is operating properly is if EGR prompted exhaust is routed through the EGR and on early C4s the temp switch is on the EGR valve or exhaust is passing through the external EGR temp switch tube on later C4s. I own an '87 with aluminum heads and the switch is on the external tube. Once that switch gets hot, it grounds, and the ecm picks up on that changed status and no check engine light will show. But if the switch is bad and can't ground out then you'll get an SES light. Also, if the switch is defective and grounded out when cold then the ecm will initiate a code 32 immediately or soon after startup.
I'm just gonna throw a new O2 sensor at mine and see what happens.
I don't have a switch on my '90.
Only reason I even said anything is because I happened to see your thread right after getting back from the drive that set off the SES and the 32 code.
I'm actally pretty darned tired of that 32 code rearing its head out of the woodwork every so often. It's the most annoying thing.
Finding a good solenoid can be a challenge, to repair a Standard Motor Products VS25 EGR solenoid. https://www.thirdgen.org/forums/tpi/...-solenoid.html
on maf tpi is seems like the temp switch fails more often than the solenoid. Just the malf code can be turned off or malf and function.
@MrRenoman as luck would have it, I just found a used EGR solenoid off an '89 that should work on my '90 on Ebay for 79 bucks. Little pricey for a used part, especially one that old, but supposedly ''works good.''
Guess I'll see.
Truth be told, I've had far better luck on 30 year old used parts than a lot of the new aftermarket imported parts that are either no good out of the box or that fail shortly therefater installation.
Which may actually be the case with that new Chinese ACDelco EGR valve I installed last year.
Code 32
