Isuzu OBD1 Trouble Codes

The following trouble codes are specific to Isuzu.

Isuzu Trouble Codes Access

Without OBD Scan Tool

To access the trouble codes, proceed as follows:

• Locate the data port connector which is under the dash or the drivers or passengers side or under the hood near the battery or firewall.
• Once the connector is located, use a jumper wire to connect the "A' and "B" terminals.
• Turn the ignition key to the on position (do not start the engine). The check engine check light will start blinking
• The first set of blinks will be the first number of the trouble code. Then a short pause will occur and the second code number will follow. For example, if the check engine light blinks two times and then a short break and then blinks two times, the code number will be 32.

To restart the code gathering process, turn the ignition key to the off position and then back on again.

Isuzu Trouble Codes Clearance

All trouble codes must be cleared from the ECU’s memory after repairing the faults. Otherwise, code(s) would remain in the ECU’s memory indefinitely and would appear along with a new code in the event of a future problem. To clear the trouble codes, proceed as follows:

• Turn the ignition key to position off.
• Disconnect the battery negative terminal for at least 20 seconds and the ECU (ECM) memory will be erased.
• Reconnect the battery negative terminal and check the codes to confirm the repair.

Warning: Disconnecting the battery may erase memory from electronic units, e.g., clock, radio.

Isuzu Generic Trouble Codes

Code(s)	Description
12	No tach signal to ECM - No Distributor Reference Pulses {4}
13	Oxygen sensor or circuit
14	Coolant Temperature Sensor Circuit High Coolant Temperature {5}
14A	High Coolant Temperature {6}
14B	Low Coolant Temperature {6}
15	Coolant Temperature Sensor Circuit Low Coolant Temperature {5} {7}
16	Same as 15
21	TP Sensor And/Or Idle Switch MAP Sensor {1} TP Sensor, Voltage High {5} {7} Throttle valve switch/Wide Open Throttle (WOT) position sensor, 1989 Manifold Absolute Pressure (MAP) circuit failure Throttle Position Sensor (TPS) - V6 models
21A	TP Sensor, Voltage High {6}
21B	TP Sensor, Voltage Low {6}
22	Starter signal system/1988 and 1989 fuel cut solenoid circuit failure TP Sensor TP Sensor, Voltage Low {5} {7} No Starter Signal {8} Fuel Cut Off Relay {4}
23	MAT Sensor MAT Sensor, Low Temp {7} M/C Solenoid Circuit {4} Mixture control solenoid circuit failure - 1987 and 1995 Amigo/Pick-up, 1989 to 1994 V6 models Power transistor circuit - 1988 to 1994 four-cylinder models Intake Air Temperature sensor voltage high - turbo, 1989 to 1995 1.6L, 1.8L, 3.2L vehicles
23A	MAT Sensor, Low Temp {6}
23B	MAT Sensor, High Temp {6}
24	Vehicle Speed Sensor (VSS) circuit - V6 models Pressure regulator vacuum switching valve - 1988 to 1994 four-cylinder, also Impulse non-turbo
25	MAT Sensor Vacuum Switching Valve {4} {9} MAT Sensor, High Temp {7} Intake Air Temperature sensor voltage high - turbo, 1989 to 1995 1.6L, 1.8L, 3.2L vehicles AIR VSV circuit failure
26	Canister Vacuum Switching Valve {4} VSV System {9}
27	VSV System {9} Constant Voltage High From VSV To ECM {4} Fuel injector driver transistor
31	No Ignition Reference Pulses To ECM {4} Wastegate Control {7} {8} No ignition reference to ECM - 1988 and 1989 models
32	Exhaust Gas Recirculation (EGR) system failure
33	MAP Sensor MAP Sensor, Voltage High {5} {7} Fuel Injector {9}
33A	MAP Sensor, Voltage High-Low {6}
33B	MAP Sensor, Voltage Low-High {6}
34	MAP Sensor {8} {11} MAP Sensor, Voltage Low {5} EGR Gas Sensor Circuit {4} {7} Fuel Injector {10}
35	MAP Sensor Constant Voltage High {4} Power Transistor System {9}
36	MAP Sensor Circuit {4}
41	Crank Angle Sensor {9} Cam Signal {7}
42	Fuel Cut Off Relay {4} Electronic Spark Timing {5} Ignition Control Circuit {6} {8}
43	Throttle valve switch/Wide Open Throttle (WOT) position sensor {9} Electronic spark control failure - V6 models Idle contact switch always closed (1988 to 1994 four-cylinder, also Impulse non-turbo) 1989 Manifold Absolute Pressure (MAP) circuit failure Knock sensor (1989 to 1995 1.6L, 3.2L) {8}
44	O2S Lean Fuel Metering {9}
45	Oxygen sensor (rich condition indicated) Fuel Metering {9}
51	PROM {2} {8} Fuel Cut Solenoid Circuit And/Or ECM {3} carbureted four-cylinder models ECM {6} MEM-CAL {7} PROM, Cal-Park & ECM {5} ROM and/or RAM {9}
52	ECM {4} EEPROM {8} ROM and/or RAM {9} PROM, Cal-Park & ECM {5}
53	Switching Valve And/Or ECM {4} Vacuum Switching Valve {9}
54	M/C (mixture control) Solenoid Circuit And/Or ECM {2} Vacuum Control Solenoid And/Or ECM {3} Power Transistor System {9} Fuel Pump, Voltage Low {5} {8} Shorted vacuum control solenoid, Faulty Electronic Control Module (ECM) - 1988 and 1989 models
55	ECM {4} {8} PROM, Cal-Park & ECM {5} Faulty Electronic Control Module (ECM) or oxygen sensor
61	Air flow sensor circuit failure {9}
62	Air flow sensor circuit failure {9}
63	Vehicle Speed Sensor (VSS) circuit {9}
64	Fuel injector driver transistor {9}
65	Throttle valve switch/Wide Open Throttle (WOT) position sensor, 1989 Manifold Absolute Pressure (MAP) circuit failure Full throttle switch always on
66	Knock sensor circuit failure {9}
71	Throttle position switch signal abnormal {9}
72	VSV for EGR system short or open {9}
73	Same as 72 transister or ground {9}

{1} - 1989 I-Mark.
{2} - I-Mark, carbureted.
{3} - Pickup, carbureted.
{4} - Carbureted models.
{5} - Throttle body fuel injection.
{6} - Rodeo & Trooper w/3.2L engine, Stylus & 1990-92 Impulse less turbocharger.
{7} - Stylus & 1990-92 Impulse w/turbocharger.
{8} - I-Mark, multi-port fuel injection.
{9} - Amigo, Pickup, Rodeo & Trooper w/2.6L engine & 1988-91 Impulse.
{10} - Impulse.
{11} - Amigo, Pickup, Rodeo & Trooper.