P24A5: EGR Cooler Bypass Control Stuck/Open (Bank 1)

P24A5 means the bank 1 cooler bypass is mechanically stuck, and makers read that in both directions. GM's 2017 Duramax DC-motor flap is judged stuck in bypass if the position is still above 15 % after P245B; the 2018 vacuum version is moved between both modes and fails when the gas temperature after the cooler barely reacts, both Type B. Ford's 2013 and 2015 diesel summaries use it as an overcooling test on the 6.7 L and 3.2 L: with the flap commanded to cooling, gas after the cooler stays below a coolant-based limit for 12 seconds, a sign the flap sits in cooling. Ford traced early cases on 2016–17 Transit 3.2 L vans (TSB 17-0009) to a wrong EGR cooler; Ram reflashed 2014 6.7 L Cummins trucks to cut needless lamps (18-053-14). Bank 2 is P24A6.

Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.

Symptoms

• Check engine light on
• Slow warm-up or more soot when the flap is stuck in cooling
• Higher NOx and EGR gas temperatures when stuck in bypass

Most likely causes

• Bypass flap seized by soot and carbon deposits
• Actuator, linkage or vacuum supply no longer moving the flap
• Incorrect EGR cooler fitted at the factory
• Engine software that sets the fault too readily

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and any vacuum hoses
2. Check the continuity of the wire between the component and the control module.
3. Use live data to compare the commanded opening with the actual opening
4. Clean the valve and passages if they are clogged with carbon
5. Test the actuator with the scanner
6. Replace the valve if it still does not follow the command after cleaning

Good to know

• Repair difficulty: hard
• It affects emissions.

What each character of P24A5 means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• A5: Specific fault in that system

Frequently asked questions

Can I keep driving with code P24A5?

You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

What causes code P24A5?

The most common causes are: bypass flap seized by soot and carbon deposits; actuator, linkage or vacuum supply no longer moving the flap; incorrect EGR cooler fitted at the factory.

Related codes

• P24A6EGR Cooler Bypass Control Stuck/Open (Bank 2)
• P245BEGR Cooler Bypass Control Circuit Range/Performance (Bank 1)
• P2457EGR Cooler A Efficiency Below Threshold
• P245AEGR Cooler Bypass Control Circuit/Open (Bank 1)
• P2493EGR Cooler Bypass Position Sensor Range/Performance (Bank 1)

Sources

• gsi.ext.gm.com: 17OBDG04 Engine Diagnostics
• gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
• fordservicecontent.com: DOBDSM1301
• fordservicecontent.com: DOBDSM1501

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.