1995 OBD1 flash fault codes -- more than one?
07-26-2023, 03:49 PM
#1
Race Car
Thread Starter
1995 OBD1 flash fault codes -- more than one?
I just wired up a check-engine light for my 1995 993 motor that's swapped into an early car tub. Sure enough, I'm now able to get error codes for the engine when I press the accelerator and turn on the ignition.
But I'm only getting one code, #43, Tank Ventilation Valve, which is not surprising, since a swapped engine no longer uses this.
But even after I disconnected the plug for the Hall Sensor on the distributor, I didn't get a second fault code.
Do other 1995 993 owners see multiple codes in the flash-pattern results? I'd like to confirm that my ECU is able to spit out more than one at a time.
Is there a simple way to provoke an additional code, as a test?
Thanks!
But I'm only getting one code, #43, Tank Ventilation Valve, which is not surprising, since a swapped engine no longer uses this.
But even after I disconnected the plug for the Hall Sensor on the distributor, I didn't get a second fault code.
Do other 1995 993 owners see multiple codes in the flash-pattern results? I'd like to confirm that my ECU is able to spit out more than one at a time.
Is there a simple way to provoke an additional code, as a test?
Thanks!
07-28-2023, 02:50 PM
#3
Race Car
Thread Starter
I can only get a single code to show at a time, and it will continue to flash until I cut power to the DME to reset it. Holding the pedal longer does not appear to reset it.
My 1143 code (Tank Ventilation Valve) still appears if nothing else is going on, or even if my Hall sensor and O2 sensors are disconnected.
If I unplug my MAF sensor, it seems to get in line ahead of the 1143 code. I got a 1121 (MAF sensor), and then -- oddly -- a 1221 after I reconnected the MAF (but still had the Hall sensor and Intake Temp sensors disconnected).
1221 is new to me. I don't have it on my list of codes, but some previous Rennlist posts connect it to the MAF and/or the DME relay.
I hope someone will see this who has seen this code before.
My 1143 code (Tank Ventilation Valve) still appears if nothing else is going on, or even if my Hall sensor and O2 sensors are disconnected.
If I unplug my MAF sensor, it seems to get in line ahead of the 1143 code. I got a 1121 (MAF sensor), and then -- oddly -- a 1221 after I reconnected the MAF (but still had the Hall sensor and Intake Temp sensors disconnected).
1221 is new to me. I don't have it on my list of codes, but some previous Rennlist posts connect it to the MAF and/or the DME relay.
I hope someone will see this who has seen this code before.
Last edited by JackOlsen; 07-28-2023 at 02:52 PM.
07-28-2023, 03:26 PM
#4
RL Community Team
Rennlist Member
Rennlist Member
Hi Jack,
Not an expert but here are my thoughts.
A failed sensor in the distributor may not be throwing a code until the system sees an increase in misfires as a result and a misfire CEL is triggered.
Even a broken distributor belt won't necessarily throw a code right away.
The oxygen sensor may not throw a code until the engine runs through a warmup period allowing the sensor to get into its operating temperature range. where the ECU allows some time before analizing the function of the sensor.
Andy
Not an expert but here are my thoughts.
A failed sensor in the distributor may not be throwing a code until the system sees an increase in misfires as a result and a misfire CEL is triggered.
Even a broken distributor belt won't necessarily throw a code right away.
The oxygen sensor may not throw a code until the engine runs through a warmup period allowing the sensor to get into its operating temperature range. where the ECU allows some time before analizing the function of the sensor.
Andy