Audi Cars 1999-05

2.8L V6 VIN H Std 4

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Trouble Code: P0420



Catalyst System Efficiency (Bank 1) Below Threshold

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is damaged, contaminated or it has failed
 
ECT/CHT sensor has lost its calibration (the signal is incorrect)
 
Engine cylinders misfiring, or the ignition timing is over retarded
 
Engine oil is contaminated
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S much older than the rear HO2S (HO2S-11 is lazy)
 
Fuel system pressure is too high (check the pressure regulator)
 
Rear HO2S wires improperly connected or the HO2S has failed
 

Trouble Code: P0421



Warm Up Catalyst System Efficiency (Bank 1) Below Threshold

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is damaged, contaminated or it has failed
 
ECT/CHT sensor has lost its calibration (the signal is incorrect)
 
Engine cylinders misfiring, or the ignition timing is over retarded
 
Engine oil is contaminated
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S much older than the rear HO2S (HO2S-11 is lazy)
 
Fuel system pressure is too high (check the pressure regulator)
 
Rear HO2S wires improperly connected or the HO2S has failed
 

Trouble Code: P0422



Main Catalyst (Bank 1) Efficiency Below Threshold

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is damaged, contaminated or it has failed
 
ECT/CHT sensor has lost its calibration (the signal is incorrect)
 
Engine cylinders misfiring, or the ignition timing is over retarded
 
Engine oil is contaminated
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S much older than the rear HO2S
 
Fuel system pressure is too high (check the pressure regulator)
 
Rear HO2S wires improperly connected or the HO2S has failed
 

Trouble Code: P0430



Catalyst System Efficiency (Bank 2) Below Threshold

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is damaged, contaminated or it has failed
 
ECT/CHT sensor has lost its calibration (the signal is incorrect)
 
Engine cylinders misfiring, or the ignition timing is over retarded
 
Engine oil is contaminated
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S much older than the rear HO2S (HO2S-11 is lazy)
 
Fuel system pressure is too high (check the pressure regulator)
 
Rear HO2S wires improperly connected or the HO2S has failed
 

Trouble Code: P0431



Warm Up Catalyst System Efficiency (Bank 2) Below Threshold

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Catalytic converter is damaged, contaminated or it has failed
 
ECT/CHT sensor has lost its calibration (the signal is incorrect)
 
Engine cylinders misfiring, or the ignition timing is over retarded
 
Engine oil is contaminated
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Front HO2S and/or the rear HO2S is loose in the mounting hole
 
Front HO2S much older than the rear HO2S (HO2S-11 is lazy)
 
Fuel system pressure is too high (check the pressure regulator)
 
Rear HO2S wires improperly connected or the HO2S has failed
 

Trouble Code: P0440



EVAP System Malfunction

Possible Causes:



EVAP canister purge valve is damaged
 
EVAP canister has an improper seal
 
Vapor line between purge solenoid and intake manifold vacuum reservoir is damaged, or vapor line between EVAP canister purge solenoid and charcoal canister is damaged
 
Vapor line between charcoal canister and check valve, or vapor line between check valve and fuel vapor valves is damaged
 
ECM has failed
 

Trouble Code: P0441



EVAP Control System Incorrect Purge Flow

Possible Causes:



EVAP canister purge valve is damaged
 
EVAP canister has an improper seal
 
Vapor line between purge solenoid and intake manifold vacuum reservoir is damaged, or vapor line between EVAP canister purge solenoid and charcoal canister is damaged
 
Vapor line between charcoal canister and check valve, or vapor line between check valve and fuel vapor valves is damaged
 
ECM has failed
 

Trouble Code: P0442



EVAP Control System Small Leak Detected

Possible Causes:



Aftermarket EVAP parts that do not conform to specifications
 
CV solenoid remains partially open when commanded to close
 
EVAP component seals leaking (i.e., leaks in the Purge valve, fuel tank pressure sensor, canister vent solenoid, fuel vapor control valve tube assembly or fuel vapor vent valve).
 
Fuel filler cap damaged, cross-threaded or loosely installed
 
Loose fuel vapor hose/tube connections to EVAP components
 
Small holes or cuts in fuel vapor hoses or EVAP canister tubes
 

Trouble Code: P0443



EVAP Vapor Management Valve Circuit Malfunction

Possible Causes:



EVAP power supply circuit is open
 
EVAP solenoid control circuit is open or shorted to ground
 
EVAP solenoid control circuit is shorted to power (B+)
 
EVAP solenoid valve is damaged or it has failed
 
ECM has failed
 

Trouble Code: P0444



Evaporative Emission System Purge Control Valve Circuit Open

Possible Causes:



EVAP power supply circuit is open
 
EVAP solenoid control circuit is open or shorted to ground
 
EVAP solenoid control circuit is shorted to power (B+)
 
EVAP solenoid valve is damaged or it has failed
 
EVAP canister has a leak or a poor seal
 
ECM has failed
 

Trouble Code: P0445



Evaporative Emission System Purge Control Valve Circuit Shorted

Possible Causes:



EVAP power supply circuit is open
 
EVAP solenoid control circuit is open or shorted to ground
 
EVAP solenoid control circuit is shorted to power (B+)
 
EVAP solenoid valve is damaged or it has failed
 
EVAP canister has a leak or a poor seal
 
ECM has failed
 

Trouble Code: P0455



EVAP Control System Large Leak Detected

Possible Causes:



Aftermarket EVAP hardware non-conforming to specifications
 
EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube disconnected or cracked, or canister is damaged
 
EVAP canister purge valve stuck closed, or canister damaged
 
Fuel filler cap missing, loose (not tightened) or the wrong part
 
Loose fuel vapor hose/tube connections to EVAP components
 
Canister vent (CV) solenoid stuck open
 
Fuel tank pressure (FTP) sensor has failed mechanically
 

Trouble Code: P0456



EVAP Control System Small Leak Detected

Possible Causes:



Aftermarket EVAP hardware non-conforming to specifications
 
EVAP canister tube, EVAP canister purge outlet tube or EVAP return tube disconnected or cracked, or canister is damaged
 
EVAP canister purge valve stuck closed, or canister damaged
 
Fuel filler cap missing, loose (not tightened) or the wrong part
 
Loose fuel vapor hose/tube connections to EVAP components
 
Canister vent (CV) solenoid stuck open
 
Fuel tank pressure (FTP) sensor has failed mechanically
 

Trouble Code: P0491



Secondary Air Injection System Insufficient Flow (Bank 1)

Possible Causes:



Air pump output is blocked or restricted
 
AIR bypass solenoid is leaking or it is restricted
 
AIR bypass solenoid is stuck open or stuck closed
 
Check valve (one or more) is damaged or leaking
 
Electric air injection pump hose(s) leaking
 
Electric air injection pump is damaged or faulty
 
ECM has failed
 

Trouble Code: P0492



Secondary Air Injection System Insufficient Flow (Bank 2)

Possible Causes:



Air pump output is blocked or restricted
 
AIR bypass solenoid is leaking or it is restricted
 
AIR bypass solenoid is stuck open or stuck closed
 
Check valve (one or more) is damaged or leaking
 
Electric air injection pump hose(s) leaking
 
Electric air injection pump is damaged or faulty
 
ECM has failed
 

Trouble Code: P0501



Vehicle Speed Sensor or PSOM Range/Performance

Possible Causes:



VSS signal circuit is open or shorted to ground
 
VSS harness circuit is shorted to ground
 
VSS harness circuit is shorted to power
 
VSS circuit open between the ECM and related control module
 
VSS or wheel speed sensors circuits are damaged
 
Modules connected to VSC/VSS harness circuits are damaged
 
Mechanical drive mechanism for the VSS is damaged
 

Trouble Code: P0506



Idle Air Control System RPM Lower Than Expected

Possible Causes:



Air inlet is plugged or the air filter element is severely clogged
 
IAC circuit is open or shorted
 
IAC circuit VPWR circuit is open
 
IAC solenoid is damaged or has failed
 
ECM has failed
 
The VSS has failed
 

Trouble Code: P0507



Idle Air Control System RPM Higher Than Expected

Possible Causes:



Air intake leak located somewhere after the throttle body
 
IAC control circuit is shorted to chassis ground
 
IAC solenoid is damaged or has failed
 
Throttle Valve Control module has failed or is clogged with carbon
 
ECM has failed
 
The VSS has failed
 

Trouble Code: P0600



Serial Communication Link (Data BUS) Message Missing

Possible Causes:



ECM has failed
 
CAN data bus wires have short circuited to each other
 

Trouble Code: P0601



Internal Control Module Memory Check Sum Error

Possible Causes:



Battery terminal corrosion, or loose battery connection
 
Connection to the ECM interrupted, or the circuit has been opened
 
Reprogramming error has occurred
 
ECM has failed and needs replacement. Remember to check for Aftermarket Performance Products before replacing a ECM.
 

Trouble Code: P0602



Control Module Programming Error

Possible Causes:



During the VID reprogramming function, the Vehicle ID (VID) data block failed during reprogramming wit the Scan Tool.
 
Battery terminal corrosion, or loose battery connection
 
Connection to the ECM interrupted, or the circuit has been opened
 
Reprogramming error has occurred
 
ECM has failed and needs replacement. Remember to check for Aftermarket Performance Products before replacing a ECM.
 

Trouble Code: P0604



Internal Control Module Random Access Memory (RAM) Error

Possible Causes:



Battery terminal corrosion, or loose battery connection
 
Connection to the ECM interrupted, or the circuit has been opened
 
Reprogramming error has occurred
 
ECM has failed and needs replacement. Remember to check for Aftermarket Performance Products before replacing a ECM.
 

Trouble Code: P0605



ECM Read Only Memory (ROM) Test Error

Possible Causes:



An attempt was made to change the module calibration, or a module programming error may have occurred
 
Clear the trouble codes and then check for this trouble code. If it resets, the ECM has failed and needs replacement.
 
Aftermarket performance products may have been installed.
 
The Transmission Control Module (TCM) has failed.
 

Trouble Code: P0606



ECM Internal Communication Error

Possible Causes:



Clear the trouble codes and then check for this trouble code. If it resets, the ECM has failed and needs replacement.
 
Remember to check for signs of Aftermarket Performance Products installation before replacing the ECM.
 

Trouble Code: P0638



Throttle Actuator Control Range/Performance Bank 1

Possible Causes:



Throttle Position (TP) sensor is faulty
 
Throttle valve control module is faulty
 
ECM is faulty
 
Circuit wires have short circuited to each other, to vehicle Ground (GND) or to B+.
 
Accelerator pedal module is faulty
 

Trouble Code: P0685



ECM Power Relay Control Circuit Open

Possible Causes:



Generator has failed or is damaged
 
Fuel pump relay is faulty
 
Circuit is grounded to power or chassis
 
ECM has failed
 

Trouble Code: P0686



ECM/PCM Power Relay Control Circuit Low

Possible Causes:



Generator has failed or is damaged
 
Fuel pump relay is faulty
 
Circuit is grounded to power or chassis
 
ECM has failed
 

Trouble Code: P0687



ECM/PCM Power Relay Control Circuit High

Possible Causes:



Generator has failed or is damaged
 
Fuel pump relay is faulty
 
Circuit is grounded to power or chassis
 
ECM has failed
 

Trouble Code: P0688



ECM/PCM Power Relay Control Sense Circuit Open

Possible Causes:



Generator has failed or is damaged
 
Fuel pump relay is faulty
 
Circuit is grounded to power or chassis
 
ECM has failed
 

Trouble Code: P1127



Long Term Fuel Trim Add. Air. Bank 1 System Too Rich

Possible Causes:



MAF sensor circuit open
 
MAF sensor circuit shorted to ground
 
Air leak in the manifold
 
Secondary air injection system combi-valve stuck open
 
Secondary air injection system electrical short
 
Fuel pressure too high, leaks in the vacuum hose to fuel pressure regulator
 
Fuel pressure regulator has failed
 
Fuel injectors are dirty, faulty or do not close properly
 
ECM has failed
 

Trouble Code: P1128



Long Term Fuel Trim Add. Air. Bank 1 System Too Lean

Possible Causes:



Fuel pressure is too low or fuel quantity supplied is too low
 
Fuel filter faulty
 
Transfer fuel pump has failed
 
Fuel injector is faulty (sticking or not opening)
 
Engine speed (RPM) sensor is faulty
 
MAF sensor circuit open
 
MAF sensor circuit shorted to ground
 
Air leak in the manifold
 
Secondary air injection system combi-valve stuck open
 
Secondary air injection system electrical short
 
ECM has failed
 

Trouble Code: P1136



Long Term Fuel Trim Add. Fuel, Bank 1 System Too Lean

Possible Causes:



Air intake system leaking, vacuum hoses leaking or damaged
 
Air leaks located after the MAF sensor mounting location
 
EGR valve sticking, EGR diaphragm leaking, or gasket leaking
 
EVAP vapor recovery system has failed
 
Excessive fuel pressure, leaking or contaminated fuel injectors
 
Exhaust leaks before or near the HO2S(s) mounting location
 
Fuel pressure regulator is leaking or damaged
 
HO2S circuits wet or oily, corroded, or poor terminal contact
 
HO2S is damaged or it has failed
 
HO2S signal circuit open, shorted to ground, shorted to power
 
Low fuel pressure or vehicle driven until it was out of fuel
 
Oil dipstick not seated or engine oil level too high (overfilled)
 

Trouble Code: P1137



Long Term Fuel Trim Add. Fuel, Bank 1 System Too Rich

Possible Causes:



Air intake system leaking, vacuum hoses leaking or damaged
 
Air leaks located after the MAF sensor mounting location
 
EGR valve sticking, EGR diaphragm leaking, or gasket leaking
 
EVAP vapor recovery system has failed
 
Excessive fuel pressure, leaking or contaminated fuel injectors
 
Exhaust leaks before or near the HO2S(s) mounting location
 
Fuel pressure regulator is leaking or damaged
 
HO2S circuits wet or oily, corroded, or poor terminal contact
 
HO2S is damaged or it has failed
 
HO2S signal circuit open, shorted to ground, shorted to power
 
Low fuel pressure or vehicle driven until it was out of fuel
 
Oil dipstick not seated or engine oil level too high (overfilled)
 

Trouble Code: P1176



O2 Correction Behind Catalyst B1 Limit Attained

Possible Causes:



O2 sensor circuit has shorted to ground or B+
 
O2 sensor circuit is open
 
ECM has failed
 
O2 sensor has failed
 
Intake Manifold Runner Position Sensor is faulty
 
Intake system for leaks (false air) is faulty
 
Motor for intake flap is faulty
 

Trouble Code: P1177



O2 Correction Behind Catalyst B2 Limit Attained

Possible Causes:



O2 sensor circuit has shorted to ground or B+
 
O2 sensor circuit is open
 
ECM has failed
 
O2 sensor has failed
 
Intake Manifold Runner Position Sensor is faulty
 
Intake system for leaks (false air) is faulty
 
Motor for intake flap is faulty
 

Trouble Code: P1196



O2 Sensor Heater Circuit (Bank 1-Sensor 1) Electrical Malfunction

Possible Causes:



HO2S heater power circuit is open
 
HO2S heater ground circuit is open
 
HO2S signal tracking (due to oil or moisture in the connector)
 
HO2S is damaged or has failed
 
ECM has failed
 
Oxygen sensor (before catalytic converter) is faulty
 
Oxygen sensor (behind catalytic converter) is faulty
 
Oxygen sensor heater (before catalytic converter) is faulty
 
Oxygen sensor heater (behind catalytic converter) is faulty
 

Trouble Code: P1197



O2 Sensor Heater Circuit (Bank 2-Sensor 1) Electrical Malfunction

Possible Causes:



HO2S heater power circuit is open
 
HO2S heater ground circuit is open
 
HO2S signal tracking (due to oil or moisture in the connector)
 
HO2S is damaged or has failed
 
ECM has failed
 
Oxygen sensor (before catalytic converter) is faulty
 
Oxygen sensor (behind catalytic converter) is faulty
 
Oxygen sensor heater (before catalytic converter) is faulty
 
Oxygen sensor heater (behind catalytic converter) is faulty
 

Trouble Code: P1199



O2 Sensor Heater Circuit (Bank 2-Sensor 2) Electrical Malfunction

Possible Causes:



HO2S heater power circuit is open
 
HO2S heater ground circuit is open
 
HO2S signal tracking (due to oil or moisture in the connector)
 
HO2S is damaged or has failed
 
ECM has failed
 
Oxygen sensor (before catalytic converter) is faulty
 
Oxygen sensor (behind catalytic converter) is faulty
 
Oxygen sensor heater (before catalytic converter) is faulty
 
Oxygen sensor heater (behind catalytic converter) is faulty
 

Trouble Code: P1201



Cylinder 1 Fuel Injection Circuit Electrical Malfunction

Possible Causes:



Injector control circuit is open
 
Injector power circuit (B+) is open
 
Injector control circuit is shorted to chassis ground
 
Injector is damaged or has failed
 
ECM is not connected or has failed
 
Fuel pump relay has failed
 
Fuel injectors may have malfunctioned
 
Faulty engine speed sensor
 

Trouble Code: P1202



Cylinder 2 Fuel Injection Circuit Electrical Malfunction

Possible Causes:



Injector control circuit is open
 
Injector power circuit (B+) is open
 
Injector control circuit is shorted to chassis ground
 
Injector is damaged or has failed
 
ECM is not connected or has failed
 
Fuel pump relay has failed
 
Fuel injectors may have malfunctioned
 
Faulty engine speed sensor
 

 
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