Warm engine to normal operating temperature and let idle. Disconnect vacuum hose "A" from 1st EGR control valve and check that engine runs smoothly. If not, replace 1st EGR control valve. See Fig 1 .

Fig 1: Checking 1st & 2nd EGR Control Valves
Courtesy of MAZDA MOTORS CORP.
Connect vacuum gauge to vacuum hose "A". Increase engine speed to 2500 RPM and check that gauge reads more than 5.9 in. Hg. If not correct, check water thermo valve, water temperature switch, No. 1 EGR solenoid valve and No. 2 EGR vacuum switch (M/T only). Reconnect vacuum hose "A" to 1st EGR control valve.
Disconnect vacuum hose "B" from 2nd EGR control valve and check that engine runs smoothly. If not, replace 2nd EGR control valve. See Fig 1 .
Connect vacuum gauge to vacuum hose "B". Increase engine speed to 2500 RPM and check that gauge reads more than 5.9 in. Hg. If not correct, check No. 2 EGR solenoid valve and No. 1 EGR vacuum switch.
Disconnect vacuum hose "C" from EGR modulator valve and plug it. Connect test hose "D" to port of EGR modulator valve. Increase engine speed to 2500 RPM. Blow into test hose "D" and check that vacuum increases. If not correct, check EGR modulator valve. Reconnect vacuum hose "C" to EGR modulator valve. See Fig 2 .

Fig 2: Inspecting EGR Modulator Valve

Courtesy of MAZDA MOTORS CORP.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

EGR System: B2600