P245C: EGR Cooler Bypass Control Circuit Low (Bank 1)

P245C reports that the control line of the bank 1 bypass actuator is pulled toward ground. GM documents this in its diesel tables: in 2014 the driver stage detects low voltage while it is switched off and treats it as a ground short, and in the 2017 tables the vacuum-switched bypass fails when the resistance to ground drops below 0.5 Ohm in 24 of 30 samples, rated Type B. With the line shorted the actuator may sit permanently in one position, so the cooler is either always bypassed or always used, which the efficiency check P2457 can then also notice. Typical findings are insulation rubbed through against the engine or exhaust, a pinched harness after repairs or a shorted solenoid winding. The open case is P245A, a short to supply P245D, and bank 2 has P2490.

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

Symptoms

• Malfunction indicator lamp on
• Bypass stuck in one position, possibly with EGR cooler efficiency code

Most likely causes

• Control wire chafed through and touching ground
• Shorted actuator or solenoid winding
• Water or corrosion bridging connector pins

What to check, in order

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

1. Check the connector and any vacuum hoses
2. With the connector unplugged, check whether the signal wire is making contact with ground.
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: medium
• It affects emissions.

What each character of P245C means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 4: Emissions
• 5C: Specific fault in that system

Frequently asked questions

Can I keep driving with code P245C?

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 P245C?

The most common causes are: control wire chafed through and touching ground; shorted actuator or solenoid winding; water or corrosion bridging connector pins.

Related codes

• P245AEGR Cooler Bypass Control Circuit/Open (Bank 1)
• P245BEGR Cooler Bypass Control Circuit Range/Performance (Bank 1)
• P245DEGR Cooler Bypass Control Circuit High (Bank 1)
• P2490EGR Cooler Bypass Control Circuit Low (Bank 2)
• P2457EGR Cooler A Efficiency Below Threshold

Sources

• gsi.ext.gm.com: 17OBDG04 Engine Diagnostics
• gsi.ext.gm.com: 14OBDG04 Engine Diagnostics
• law.cornell.edu: 13 CCR 1968.2

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.