How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician shows how to replace the G28 Engine Speed Sensor. The sensor is located at the edge of transmission just above the flywheel gear. It sends a message to the ECU via a grey wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
It is located on the outside of the transmission just above the flywheel ring gear the G28 Engine Speed Sensor sends an electrical signal to ECU pin T55/49 through a grey wire. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 tachometer in the instrument cluster.
The sensor is used to correlate the G40 Camshaft position Sensor. The ecu needs to be aware of when the crankshaft has reached TDC and also the position of the camshaft, in order to activate the spark and injectors.
If this sensor fails, the ECU will show a P00160 code which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain is stretched or a jump link on the upper timing chain. The code will not appear without the additional information provided by other sensors (G4 or G40).
It's a bit tricky to test since there are various pins on the connector and they all have different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. It should read around 1000 ohms when it is in full operation. If you're having issues with this sensor, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, when accelerating from highway paytoll at full speed I noticed a significant drop in power. It was as if the engine was running out of gas. Or, my injectors weren't firing. Today, i pulled out the spark plugs. Three were drenched in gazoline, the fourth one was dry. I placed a tissue over each injector hole, and when i start the engine with no sparks, the 3 that have gazoline pop right out. The 4th one stays shut. I tested the ground connection of ECU pins 14,30 and 48/55. I got zero ohm. So i assume the problem is elsewhere.
I also tried to reset the PID with no success. The car will start when the G28 is unplugged, and it works fine when the G28 connected. However, the intermittent misfire problem persists at higher RPM. The coolant sensor (G62) even when unplugged, still shows a temperature of -49c. I also noticed that the gauge for oil pressure in the cockpit shows 2 bar when the actual pressure is 0.0 when I crank up the engine.
I don't know what to do. I think I've eliminated everything else. I'm concerned that i may have missed something. If anyone has suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump on the g28 is activated by a signal sent from the RPM sensor. The GM-style sender is identical to the G4 and both are used in the 80, 100 200, UrS and RS2 cars which is why you can easily locate one at a junkyard or in a local parts store. It is simple to test them to do - just put your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from the left on the black end of the connector). They must be infinite Ohms.
4. ECU
The ECU of our 20vt turbo (3B AAN ABY ADU) engines needs to know both the position and speed the crankshaft to make decisions regarding more info timing of fuel injectors, etc. To accomplish this, it utilizes a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these go wrong, you will receive codes on the diagnostic scanner that can lead to engine shutdown.
A damaged G28 sensor could cause an inaccurate speed counter for the gearbox, a gearbox that shifts more quickly than normal, and/or a misfire in gear. If you have any of these issues it is likely that your sensor is failing and requires replacement. here They're inexpensive and easy to locate especially if they're a Bosch model like ours. Alternately, GM's version this component is an option.
5. Tachometer
A malfunctioning engine speed sensor could be a cause for a slew of problems in your car. It's an essential component of the transmission of your Audi since it sends information to the ECU regarding how fast or slowly the engine of the car is turning. This sensor could cause check here the transmission to fail and other components in the car to be affected.
The G5 engine speed sensor is located on the edge of the transmission, above the flywheel ring gear and transmits a signal to the ECU at pin T55/49, via an uncolored wire. The ECU uses this signal to control the lost audi keys amount of fuel and boost, and also to timigrate. It also transmits it to the G5 Tachometer inside the instrument cluster. You can test for sensor failure by examining the continuity from the sensor to the tachometer. You can also examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and between pin T6a/1 as well as pin T26a/12. It should show approximately 1000 ohms of resistance between those two pins. This is the same across the Audi 80-100-200-RS2 audi lost key model, ranging from the 1985 MC up to the 1997 UrS AN and 1995 RS2 Du So, you may find them in wrecking yards.