Sorry, I posted the wrong codes for Pin 4, below are the correct ones, I also updated my previous post;
The little LED is giving you a code 3, or asking you to check the LH-SFI unit (Codes for the LH-SFI unit come from Pin 4)

The LH-SFI ECU contains several programs and functions as described in the following:
- Voltage Supply (+12.5V)
- Starter circuit
- Engine temperature from coolant temperature sensor (B11/2)
- Intake air temperature from intake manifold temperature sensor (B17/7)
- Intake air mass from mass air sensor (B2/2)
- Various information from the controller area network (CAN)
- ABS/ASR information from ABS/ASR control module (N30/1)
- Air/fuel mixture from oxygen sensor (G3/2)
- ON signal from air injection
- ON signal for exhaust gas recirculation (EGR)


Socket 1: Black (Ground)
Socket 3: Red (+12.5V)
Socket 4: Yellow (Pin for LH-SFI DTC readout)

DTC Readout Possible Cause
1 No Faults in System
2 ECT sensor (B11/2) sensor circuit 1, open/short circuit
3 ECT sensor (B11/2) sensor circuit 2, open/short circuit
4 Voltage at hot wire MAF sensor (B2/2) insufficient or too high, or open circuit in ground wire at hot wire MAF sensor
5 Not used
6 Not used
7 TN-signal (rpm signal) incorrect or open/short circuit
8 CMP sensor (L5/1), open/short circuit
9 Starter signal (circuit 50) missing, open/short circuit
10 CTP (idle) recognition from EA/CC/ISC control module (N4/1), short circuit
11 Secondary air injection system, open/short circuit
12 Burn-off control for hot wire MAF sensor, open/short circuit
13 IAT sensor (B17/7), open/short circuit
14 Not used
15 Not used
16 EGR switchover valve (Y27), open/short circuit
17 No CAN data transmission with EA/CC/ISC control module (N4/1) or N4/3)
18 No CAN data transmission with DI control module (N1/3)
19 Not used
20 No CAN data transmission with LH-SFI control module (N3/1)
21 O2S 1 (before TWC) (G3/2), open/short circuit
22 O2S 1 heater, open/short circuit
23 Purge control valve (Y68/1), open/short circuit
24 Left adjustable camshaft timing solenoid (Y49/1), open/short circuit
25 Right adjustable camshaft timing solenoid (Y49/2), open/short circuit
26 Upshift delay switchover valve (Y3/3), open/short circuit
27 Injectors (Y62), open/short circuit
28 LH-SFI control module coding, open circuit
29 1GR start relay module (K29/1), open/short circuit

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified