U18A2: On Chevrolet, U18A2 means the engine computer lost communication with the fuel pump driver control module
Lost communication with fuel pump driver control module (GM)
Severity: Inspect soon
Chevrolet owners report a stall with no warning, including at about 35 mph and on the highway, and a no-start; fuel delivery loss is a safety risk in traffic, so have it checked soon.
It gets more serious if:
- Stop: Stop if the engine stalls while driving, or you smell fuel or see fuel leaking: do not keep restarting it; get it towed.
U18A2 in short
On Chevrolet, U18A2 means the engine computer lost contact with the fuel pump driver control module, so the pump may not run. The likeliest fix is a failed module, though a loose connector or power fault is possible. Owners report stalling and no-start, so have it checked soon and stop if it stalls.
GM trucks and SUVs use a separate module to power and control the fuel pump. The engine computer sends it commands over the network. If it hears nothing back, it stores U18A2.
With the pump unpowered the engine can stall or refuse to start. GM's own article for 2021-2024 2.0L models lists U18A2 as a code that may be set with P023F or P129F, and replaces the fuel pump driver control module when diagnostics confirm it.
An older GM communication for 2014-2016 trucks and SUVs says to follow published diagnostics when P2635, U0074 and/or U18A2 are stored, and that U0074 takes priority over U18A2.
Pick your make
U18A2 is a manufacturer-specific code: its meaning depends on who built the car.
Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.
Most likely causes
Cause 1: Fuel pump driver control module failure
Supported by vehicle data- Why it ranks here
- GM's article names replacing the fuel pump driver control module for crank/no-start with these codes on 2021-2024 2.0L models, and Chevrolet owners report a new module ordered after U18A2 stalls.
- What would change this
- Rises if P023F or P129F are stored too and the module fails dealer tests. Falls if power, ground and the network to it test good only after a connector repair.
Cause 2: Loose connector or lost power to the module
Possible — needs testing- Why it ranks here
- A dealer told one Volt owner a loose electrical connector was behind U18A2, and AA1Car notes a code does not say which part failed. It is one report, so it ranks below the module.
- What would change this
- Rises if the fault is intermittent or follows bumps or fuse work. Falls if the module fails when tested with good power.
Cause 3: A wider network communication fault
Common general cause- Why it ranks here
- GM tells technicians to deal with U0074 first if it is set with U18A2, which means a network-wide fault can hide behind this code.
- What would change this
- Rises if U0074 or other lost-communication codes are stored. Falls if U18A2 is the only network code.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all stored codes and note whether U0074, P2635, P129F or P023F are stored with U18A2.
IfU0074 is stored too
It meansGM says to diagnose the wider communication fault first.
IfP129F or P023F is stored, or U18A2 is the only code
It meansHave a dealer test the module.
Step 2: Ask a Chevrolet dealer to test power, ground and communication at the fuel pump driver control module and check for bulletins or emissions-warranty coverage on your VIN.
Warning:Fuel system parts hold fuel under pressure and can leak fuel near ignition sources. Leave testing to a shop.
IfThe module fails its tests with good power and ground
It meansThe module is the fault.
IfA loose terminal or lost power is found
It meansRepair the circuit and retest.
Symptoms
- Engine cranks but does not start
- Engine stalls with no warning Gets more serious: stop and have it checked.
- Smell of fuel or fuel leaking after a stall Gets more serious: stop and have it checked.
- Check engine light after the stall
Compare with: Check engine light with loss of power
How to fix
Step 1: Ask a dealer whether your VIN has an open bulletin or emissions-warranty coverage for the fuel pump driver control module; GM states the replacement is covered by the Federal Emission Warranty (8 years/80,000 miles).
Parts and cost context
- Fuel pump:The part is the fuel pump driver control module, not the pump itself. Labor varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
ChevroletYour car
2014–2016
Supported by vehicle dataGM information PIP5427 covers 2014-2016 Silverado, Tahoe and Suburban (and GMC and Cadillac twins) with P2635, U0074 and/or U18A2. Whether it is still current is not verified.
PIP5427Status unverified
SES light with P2635, U0074 and/or U18A2
2014–2016silverado-1500, silverado-2500-hd, silverado-3500-hd, tahoe, suburban · NHTSA 10099961
Preliminary information for technicians: follow published diagnostics when P2635, U0074 and/or U18A2 are stored, with U0074 taking priority over U18A2.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
U18A2 questions
Is it safe to drive with U18A2?
Owners report stalls at speed and no-starts, so it is not a code to ignore. Get it checked soon, and have the car towed if it stalls or you smell fuel.
Sources and review
- NHTSA complaint ODI 11744381: 2022 Chevrolet Blazer
- NHTSA complaint ODI 11654420: 2020 Chevrolet Equinox
- Fuel Pump Power Control Module Internal Short
- NHTSA complaint ODI 11465611: 2019 Chevrolet Equinox
- NHTSA complaint ODI 11075848: 2017 Chevrolet Volt
- CAN bus U-codes
- GM PIP5427: SES light with P2635, U0074 and/or U18A2 (2014-2016 full-size trucks and SUVs)
- NHTSA complaint ODI 11599344: 2017 Chevrolet Silverado 2500
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error