GM ERROR CODES

DIAGNOSTICS
Summary of error codes (OBD-1 systems)

ERROR	DESC.	ERROR	DESC.	ERROR	DESC.	ERROR	DESC.
13	o2 SENSOR	33	HIGH MAP	56	QUAD DRIVER B FAULT (not used)	75	SYSTEM VDC LOW
14	COOL SENSOR, HIGH	34	LOW MAP	57	not used	76	not used
15	COOL SENSOR, LOW	35	IAC ERROR	58	XMISH TEMP HI	77	NMP SWITCH
16	Vss	36	not used	59	XMISH TEMP LOW	78	not used
17	RPM SIGNAL PROBLEM (not used)	37	BRAKE SW STUCK ON, TCC	61	TURBO BOOST SENSOR HI	79	XMISH HOT
18	CAM CRANK ERROR (not used)	38	BRAKE SW STUCK OFF, TCC	62	TURBO BOOST SENSOR LOW	81	SHIFT SOLENOID B FAIL
19	not used	39	TCC STUCK OFF	63	BARO SENSOR HI	82	SHIFT SOLENOID A FAIL
21	TPS HIGH	41	1x CAM SENSOR FAIL	64	BARO SENSOR LOW	83	TCC SOLENOID FAIL
22	TPS LOW	42	SPARK MONITOR	65	not used	84	not used
23	MAT LOW	43	KNOCK SENSOR	66	3-2 DS QDM2/SOLENOID FAIL	85	RATIO UN-DEFINED REGION
24	LOW Vss	44	o2 LOW (Lean)	67	TCC EN QDM2/SOLENOID FAIL	86	SOLENOID B STUCK ON
25	MAT HIGH	45	o2 HIGH (Rich)	68	XMISH COMPONENT SLIPPING	87	SOLENOID B STUCK OFF
28	TRANS PRESSURE SW MANIFOLD	46	VATS	69	TCC ON	88	not used
29	not used	47	not used	71	ENGINE SPEED LOW	89
31	GOVERNOR	53	HI SYS VOLTAGE	72	OUTPUT SPEED LOSS	91	not used
32	EGR	54	LOW FUEL PUMP VOLTAGE	73	FORCE MOTOR CURRENT	92	not used
32B	LINEAR EGR PINTLE POSITION	55	FAULTY COMPUTER (ADU)	74	INPUT SPEED SENSOR

o2 SENSOR CODE 13

Tested after run time GT 120 Sec's

Coolant gt 70c

o2 low limit 350 mvdc

o2 high limit 550 mvdc

60 Sec test period

COOL SENSOR, HIGH CODE 14

Time since run limit (typically 1 second)

High coolant threshold, usually GT 135c

COOL SENSOR, HIGH CODE 15

Time since run limit (typically 1 second)

High coolant threshold, usually LT 35c

VSS Sensor CODE 16

Coolant gt 70c

RPM test window 950 - 4400 rpm

2 MPH min

RPM SIGNAL PROBLEM CODE 17

CAM CRANK ERROR CODE 18

High TPS Sensor Voltage CODE 21

TPS threshold, 2.5 VDC, (50%)

time limit, 8 seconds

Baro limits, 52 Kpa

Low TPS Sensor Voltage CODE 22

TPS threshold, 200 mvdc

TPS threshold, 960 mvdc

Vehicle Speen Sensor (Vss) Error CODE 24

Vss Threshold, 4 MPH

RPM low threshold    1400 RPM

RPM High threshold   6000 RPM

MAP threshold            25 Kpa

Coolant Threshold        65c

Test time limit           5 Seconds

EGR CODE 32

MAP window typically 40 to 90 Kpa for test enable

Minimum Vss for test, 45 MPH

Test duration, 3 seconds

Integrator shift for 100% EGR during test, (BP EGR System)

EGR CODE 32B (Linerar EGR)

MAP HIGH CODE 33

Set if the MAP sensor voltage is high (68 Kpa) for 5 seconds or more and TPS is not at a high throttle setting.

4% TPS max

If sensor vacuum hose is disconnected for 5 seconds or more.

MAP LOW CODE 34

Set if the MAP sensor voltage (l.t. 12 Kpa) is very low or missing, (MAP sensor unpluged).

1200 RPM upper RPM limit

500 msec period

8 pct TPS max

Electronic Spark Timing Monitor
This test elavualtes communications between the Distributor module and the ECM/PCM.
It is most frequently set when the spark by-pass signal is open for initail timing adjustment.

SPARK MONITORCODE 42

Minimum RPM for test, 450 RPM, (Don't test if in engine start up.)

Electronic Spark Control, (Knock Sensor)
Usually fails if knock module (or knock sensor) is not connected. KNOCK SENSORCODE 43

Miniumum Run time, 4 minutes

Test period, 2 seconds

Knock counter threshold

Coolant low threshold for test, 84c

Coolant High threshold for test, 105c

RPM threshold 3200 RPM

MAP upper threshold 82 Kpa

Spark to force knock

12 - 22 Degrees

Requires 2 Knock signals to pass

O2 SENSOR LEAN CODE 44

Low o2 Voltage, 148 mvdc

Miniumum Run time

Minimum Time, 20 Seconds

O2 SENSOR RICH CODE 45

High o2 Voltage, 750 mvdc

Miniumum Run time

Minimum Time, 60 Seconds

TPS window 0 - 5%