Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / P0477 — Exhaust Pressure Control Valve A Low

P0477 — Exhaust Pressure Control Valve A Low

Detailed page for trouble code P0477.

34,405codes
59brands
11,914generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

P0477

Generic P — Powertrain

Exhaust Pressure Control Valve A Low

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground in exhaust pressure control valve A wiring or connector
  • Open circuit or high resistance in the valve control wiring
  • Failed exhaust pressure control valve (stuck closed or open, electrical failure)
  • Poor connector contact or corrosion at the valve or ECM connector
  • Failed exhaust pressure sensor or related feedback circuit (if used)
  • Blown fuse or low supply/reference voltage to the valve

Symptoms

  • MIL (Check Engine Light) ON
  • Reduced engine performance or turbo control (possible limp mode)
  • Reduced boost or incorrect exhaust backpressure control
  • Poor fuel economy
  • Possible turbo surge, lag, or abnormal exhaust noise

What to check

  • Read and record freeze frame and pending/confirmed codes with a scan tool
  • Verify code is current: clear code and perform drive cycle to see if it returns
  • Inspect valve connector and wiring for damage, corrosion, or disconnection
  • Visually inspect vacuum/pressure hoses or lines associated with the valve for leaks or blockages
  • Use a scan tool to monitor valve command and feedback data (actuator position, sensor voltage)
  • Check for applicable fuses and relays supplying the valve

Signal parameters

  • Expected actuator command: PWM or switched signal from ECM (0–12 V range depending on vehicle)
  • Expected sensor/feedback voltage (if present): typically ~0.5–4.5 V depending on pressure range; a constant near 0 V indicates a low/short condition
  • Typical solenoid coil resistance (generic): about 5–50 ohms — consult vehicle-specific data
  • Reference supply commonly 5 V or battery voltage depending on circuit — measure at connector with key ON

Diagnostic algorithm

  1. Connect a scan tool, read codes and freeze frame data. Note engine conditions when code set.
  2. Attempt to actuate the exhaust pressure control valve using a bi-directional control on the scan tool while monitoring commanded signal and feedback. Note any lack of movement or response.
  3. Visually inspect valve, connector, and wiring harness for damage, corrosion, or contamination. Repair any obvious issues.
  4. With key ON (engine OFF), measure supply voltage and ground at the valve connector. Compare to expected reference (battery voltage or 5 V reference).
  5. Check continuity and resistance of the valve coil/actuator between the valve pins and to ground. Compare to manufacturer specs. Look for short to ground or open circuit.
  6. Backprobe the control circuit while commanding the valve to operate; verify the ECM is providing the proper control signal (PWM or switching).
  7. If feedback sensor is present, measure sensor output voltage while applying known exhaust pressure or using a pressure source; verify response and range.
  8. Repair wiring/connectors or replace the valve if the actuator is out of specification. Replace fuses or restore supply/ground as needed.
  9. If wiring and valve test good, suspect ECM output fault; confirm with wiring back-probing and replace ECM only after exhaustive verification.
  10. Clear codes and perform a road or diagnostic drive cycle to confirm repair.

Likely causes

  • Damaged or shorted wiring at the valve connector
  • Failed solenoid/actuator in the exhaust pressure control valve
  • Corroded/poor connector contacts
  • Blown fuse or missing power/ground to the valve

Fault status

⚠️ Status
Exhaust Pressure Control Valve A Circuit Low — low/shorted signal or insufficient voltage detected in the valve/sensor circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.0 hours

Similar codes

P0476 P0234 P0299 P2263 P0107
9,043

The library contains 9,043 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.

ALFA ROMEO
89
AUDI
1,243
BMW
479
CADILLAC
206
CHEVROLET
456
CHRYSLER
129
DAEWOO
75
FIAT
26
GENESIS
207
HUMMER
138
HYUNDAI
371
ISUZU
86
LAND ROVER
320
LEXUS
280
LINCOLN
166
MERCEDES-BENZ
856
MERCURY
296
MITSUBISHI
406
PORSCHE
136
TESLA
58
TOYOTA
2,042
TRIUMPH
131
VOLKSWAGEN
626
VOLVO
221
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P0477

GWM P — Powertrain

- Low Indicator for Exhaust Pressure Control Valve

Brand: GWM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground in exhaust pressure control valve A wiring or connector
  • Open circuit or high resistance in the valve control wiring
  • Failed exhaust pressure control valve (stuck closed or open, electrical failure)
  • Poor connector contact or corrosion at the valve or ECM connector
  • Failed exhaust pressure sensor or related feedback circuit (if used)
  • Blown fuse or low supply/reference voltage to the valve

Symptoms

  • MIL (Check Engine Light) ON
  • Reduced engine performance or turbo control (possible limp mode)
  • Reduced boost or incorrect exhaust backpressure control
  • Poor fuel economy
  • Possible turbo surge, lag, or abnormal exhaust noise

What to check

  • Read and record freeze frame and pending/confirmed codes with a scan tool
  • Verify code is current: clear code and perform drive cycle to see if it returns
  • Inspect valve connector and wiring for damage, corrosion, or disconnection
  • Visually inspect vacuum/pressure hoses or lines associated with the valve for leaks or blockages
  • Use a scan tool to monitor valve command and feedback data (actuator position, sensor voltage)
  • Check for applicable fuses and relays supplying the valve

Signal parameters

  • Expected actuator command: PWM or switched signal from ECM (0–12 V range depending on vehicle)
  • Expected sensor/feedback voltage (if present): typically ~0.5–4.5 V depending on pressure range; a constant near 0 V indicates a low/short condition
  • Typical solenoid coil resistance (generic): about 5–50 ohms — consult vehicle-specific data
  • Reference supply commonly 5 V or battery voltage depending on circuit — measure at connector with key ON

Diagnostic algorithm

  1. Connect a scan tool, read codes and freeze frame data. Note engine conditions when code set.
  2. Attempt to actuate the exhaust pressure control valve using a bi-directional control on the scan tool while monitoring commanded signal and feedback. Note any lack of movement or response.
  3. Visually inspect valve, connector, and wiring harness for damage, corrosion, or contamination. Repair any obvious issues.
  4. With key ON (engine OFF), measure supply voltage and ground at the valve connector. Compare to expected reference (battery voltage or 5 V reference).
  5. Check continuity and resistance of the valve coil/actuator between the valve pins and to ground. Compare to manufacturer specs. Look for short to ground or open circuit.
  6. Backprobe the control circuit while commanding the valve to operate; verify the ECM is providing the proper control signal (PWM or switching).
  7. If feedback sensor is present, measure sensor output voltage while applying known exhaust pressure or using a pressure source; verify response and range.
  8. Repair wiring/connectors or replace the valve if the actuator is out of specification. Replace fuses or restore supply/ground as needed.
  9. If wiring and valve test good, suspect ECM output fault; confirm with wiring back-probing and replace ECM only after exhaustive verification.
  10. Clear codes and perform a road or diagnostic drive cycle to confirm repair.

Likely causes

  • Damaged or shorted wiring at the valve connector
  • Failed solenoid/actuator in the exhaust pressure control valve
  • Corroded/poor connector contacts
  • Blown fuse or missing power/ground to the valve

Fault status

⚠️ Status
Exhaust Pressure Control Valve A Circuit Low — low/shorted signal or insufficient voltage detected in the valve/sensor circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.0 hours

Similar codes

P0476 P0234 P0299 P2263 P0107
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P0477

HUMMER P — Powertrain

Exhaust Pressure Control Valve Low

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground in exhaust pressure control valve A wiring or connector
  • Open circuit or high resistance in the valve control wiring
  • Failed exhaust pressure control valve (stuck closed or open, electrical failure)
  • Poor connector contact or corrosion at the valve or ECM connector
  • Failed exhaust pressure sensor or related feedback circuit (if used)
  • Blown fuse or low supply/reference voltage to the valve

Symptoms

  • MIL (Check Engine Light) ON
  • Reduced engine performance or turbo control (possible limp mode)
  • Reduced boost or incorrect exhaust backpressure control
  • Poor fuel economy
  • Possible turbo surge, lag, or abnormal exhaust noise

What to check

  • Read and record freeze frame and pending/confirmed codes with a scan tool
  • Verify code is current: clear code and perform drive cycle to see if it returns
  • Inspect valve connector and wiring for damage, corrosion, or disconnection
  • Visually inspect vacuum/pressure hoses or lines associated with the valve for leaks or blockages
  • Use a scan tool to monitor valve command and feedback data (actuator position, sensor voltage)
  • Check for applicable fuses and relays supplying the valve

Signal parameters

  • Expected actuator command: PWM or switched signal from ECM (0–12 V range depending on vehicle)
  • Expected sensor/feedback voltage (if present): typically ~0.5–4.5 V depending on pressure range; a constant near 0 V indicates a low/short condition
  • Typical solenoid coil resistance (generic): about 5–50 ohms — consult vehicle-specific data
  • Reference supply commonly 5 V or battery voltage depending on circuit — measure at connector with key ON

Diagnostic algorithm

  1. Connect a scan tool, read codes and freeze frame data. Note engine conditions when code set.
  2. Attempt to actuate the exhaust pressure control valve using a bi-directional control on the scan tool while monitoring commanded signal and feedback. Note any lack of movement or response.
  3. Visually inspect valve, connector, and wiring harness for damage, corrosion, or contamination. Repair any obvious issues.
  4. With key ON (engine OFF), measure supply voltage and ground at the valve connector. Compare to expected reference (battery voltage or 5 V reference).
  5. Check continuity and resistance of the valve coil/actuator between the valve pins and to ground. Compare to manufacturer specs. Look for short to ground or open circuit.
  6. Backprobe the control circuit while commanding the valve to operate; verify the ECM is providing the proper control signal (PWM or switching).
  7. If feedback sensor is present, measure sensor output voltage while applying known exhaust pressure or using a pressure source; verify response and range.
  8. Repair wiring/connectors or replace the valve if the actuator is out of specification. Replace fuses or restore supply/ground as needed.
  9. If wiring and valve test good, suspect ECM output fault; confirm with wiring back-probing and replace ECM only after exhaustive verification.
  10. Clear codes and perform a road or diagnostic drive cycle to confirm repair.

Likely causes

  • Damaged or shorted wiring at the valve connector
  • Failed solenoid/actuator in the exhaust pressure control valve
  • Corroded/poor connector contacts
  • Blown fuse or missing power/ground to the valve

Fault status

⚠️ Status
Exhaust Pressure Control Valve A Circuit Low — low/shorted signal or insufficient voltage detected in the valve/sensor circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.0 hours

Similar codes

P0476 P0234 P0299 P2263 P0107
Repair manuals

Manual library for HUMMER

138

Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HUMMER

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P0477

MERCEDES-BENZ P — Powertrain

Exhaust Pressure Control Valve Low

Brand: MERCEDES-BENZ
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground in exhaust pressure control valve A wiring or connector
  • Open circuit or high resistance in the valve control wiring
  • Failed exhaust pressure control valve (stuck closed or open, electrical failure)
  • Poor connector contact or corrosion at the valve or ECM connector
  • Failed exhaust pressure sensor or related feedback circuit (if used)
  • Blown fuse or low supply/reference voltage to the valve

Symptoms

  • MIL (Check Engine Light) ON
  • Reduced engine performance or turbo control (possible limp mode)
  • Reduced boost or incorrect exhaust backpressure control
  • Poor fuel economy
  • Possible turbo surge, lag, or abnormal exhaust noise

What to check

  • Read and record freeze frame and pending/confirmed codes with a scan tool
  • Verify code is current: clear code and perform drive cycle to see if it returns
  • Inspect valve connector and wiring for damage, corrosion, or disconnection
  • Visually inspect vacuum/pressure hoses or lines associated with the valve for leaks or blockages
  • Use a scan tool to monitor valve command and feedback data (actuator position, sensor voltage)
  • Check for applicable fuses and relays supplying the valve

Signal parameters

  • Expected actuator command: PWM or switched signal from ECM (0–12 V range depending on vehicle)
  • Expected sensor/feedback voltage (if present): typically ~0.5–4.5 V depending on pressure range; a constant near 0 V indicates a low/short condition
  • Typical solenoid coil resistance (generic): about 5–50 ohms — consult vehicle-specific data
  • Reference supply commonly 5 V or battery voltage depending on circuit — measure at connector with key ON

Diagnostic algorithm

  1. Connect a scan tool, read codes and freeze frame data. Note engine conditions when code set.
  2. Attempt to actuate the exhaust pressure control valve using a bi-directional control on the scan tool while monitoring commanded signal and feedback. Note any lack of movement or response.
  3. Visually inspect valve, connector, and wiring harness for damage, corrosion, or contamination. Repair any obvious issues.
  4. With key ON (engine OFF), measure supply voltage and ground at the valve connector. Compare to expected reference (battery voltage or 5 V reference).
  5. Check continuity and resistance of the valve coil/actuator between the valve pins and to ground. Compare to manufacturer specs. Look for short to ground or open circuit.
  6. Backprobe the control circuit while commanding the valve to operate; verify the ECM is providing the proper control signal (PWM or switching).
  7. If feedback sensor is present, measure sensor output voltage while applying known exhaust pressure or using a pressure source; verify response and range.
  8. Repair wiring/connectors or replace the valve if the actuator is out of specification. Replace fuses or restore supply/ground as needed.
  9. If wiring and valve test good, suspect ECM output fault; confirm with wiring back-probing and replace ECM only after exhaustive verification.
  10. Clear codes and perform a road or diagnostic drive cycle to confirm repair.

Likely causes

  • Damaged or shorted wiring at the valve connector
  • Failed solenoid/actuator in the exhaust pressure control valve
  • Corroded/poor connector contacts
  • Blown fuse or missing power/ground to the valve

Fault status

⚠️ Status
Exhaust Pressure Control Valve A Circuit Low — low/shorted signal or insufficient voltage detected in the valve/sensor circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.0 hours

Similar codes

P0476 P0234 P0299 P2263 P0107
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .