P045F: EGR B Control Stuck Closed

Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. EGR B is a second EGR valve next to valve A – on diesels with two EGR circuits the low-pressure valve, which takes exhaust after the particulate filter and feeds it in before the turbo compressor. GM's diesels of 2016–18 and FCA's 2.2-litre diesel in the Jeep Wrangler use it. P045F means valve B does not open: its actual position stays below the target despite the open command. GM lists the code among those that switch off low-pressure EGR control; Ford's comparable valve A check (P042F) compares the position with a calculated lower limit. Too little EGR raises NOx while driving stays normal. Icing or condensate can block a low-pressure valve – FCA runs its cleaning routine only above 0 °C.

Symptoms

• Check engine light on
• Low-pressure EGR switched off, possibly higher NOx
• Usually no change in driving

Most likely causes

• Low-pressure valve coked or stuck
• Actuator motor or gear faulty
• Icing or condensate in the low-pressure circuit
• Position sensor reports a wrong position

What to check, in order

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

1. Check the connector and any vacuum hoses
2. Use the scanner to command the movement and compare the actual position with the requested one.
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 P045F means

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

Frequently asked questions

Can I keep driving with code P045F?

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 P045F?

The most common causes are: low-pressure valve coked or stuck; actuator motor or gear faulty; icing or condensate in the low-pressure circuit.

Related codes

• P045EEGR B Control Stuck Open
• P042FEGR A Control Stuck Closed
• P0401EGR A Flow Insufficient Detected
• P044CEGR Sensor C Circuit Low
• P049EEGR B Control Position Exceeded Learning Limit

Sources

• gsi.ext.gm.com: 18OBDG04 Engine Diagnostics
• law.cornell.edu: 13 CCR 1968.2
• patents.google.com: en
• static.nhtsa.gov: MC 10162563 9999

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.