How to Replace an Audi G28 Engine Speed Sensor

In this video, Charles the Humble Mechanic shows how to replace the G28 engine speed sensor. The sensor is located on the outside of the transmission just above the flywheel gear. It transmits a signal to the ECU via an uncolored wire T55/49, then to the tachometer located on the instrument cluster.

1. Engine Speed Sensor

The grey wire is situated at the edges of the transmission, directly above the flywheel ring. This sensor sends signals through the grey wire to pin T55/49. The ECU then utilizes this information to regulate fuel, timig and boost. It also sends an indication to the G5 Tachometer within the instrument cluster.

The sensor is used to link the G40 Camshaft position Sensor. The ecu needs to know when the crankshaft is TDC and where the camshaft is located so that it can activate spark and injectors according to the situation.

If this sensor fails, the ECU will display an error code P00160. This means that the Crank Shaft is out of line with the Intake Camshaft. It could also indicate a chain stretch or a jump in the chain link of the upper timing chain. However, the code won't appear on its own without additional information from other sensors (G4 and G40).

It's a bit tricky to test as there are different pins on the connector and each one has different functions. The best method for doing this is to measure the resistance between the ECU and the sensor. If the sensor is operational, it should be reading about 1000 ohms. Examine for signs of coolant, or oil in the connector bay if there are issues with this component.

2. Injectors

Yesterday, when i was accelerating to the fullest speed from highway paytoll, I experienced an abrupt drop in power as if the engine was running out of gas or the injectors are not firing at all. This morning i pull out the spark plugs, three were soaked with gazoline and the fourth was dry. I put tissue over each hole in the injector and when I start the engine without sparks, the ones that have gazoline pop right out. The fourth one remains closed. I tested the ground connection of ECU pins 14,30, and 48/55. I got zero ohm. I assume that the problem is in another location.

I also tried to reset the PID but without success. The car will start if the G28 is unplugged and runs fine when it is connected but it still is experiencing intermittent misfires at higher RPM. The temperature sensor for the coolant (G62) shows the wrong temperature value of -49c even when i unplug it. I also noticed that the oil gauge in the cockpit shows 2 bar while the actual pressure is 0.

I'm not sure what to do. I feel like i've pretty much all other possibilities out. But i am afraid I may have missed something. If anyone has suggestions, please share them! TIA!

3. Fuel Pump

The fuel pump of the g28 receives signals from the RPM sensor. The GM-style sensor is identical to the G4 and both function in the 80 100 200, UrS and RS2 cars so you can easily find one at a salvage yard or at a parts store. Testing them is easy by putting your DMM in resistance mode and measure between pins 1 (with the bump on the connector's end up) and 2 (2nd from left on the black end of the connector). They must be infinite Ohms.

4. ECU

Our 20vt turbo (3B AAN, ABY and ADU) engines have an ECU that needs to know the speed and position of the crankshaft to make decisions regarding timing of the fuel injector, for example. To do this, it makes use of a Crank Position Sensor (G4) and an Engine Speed Sensor (G28). If either of these sensors go bad you will get codes on the diagnostic scanner which could cause engine shut down.

Some of the signs of a failed G28 sensor are an inaccurate rev counter for the gearbox and gears that shift faster than normal and/or misfiring when you are in gear. If you are experiencing any of these problems, it is likely your sensor [Redirect-302] is deteriorating and should be replaced. The good thing is that they are quite affordable and easy to find particularly if you're looking at a Bosch unit which is what ours are. You can also choose the GM version of this part is also a great option.

5. Tachometer

A damaged engine sensor could cause a number of problems in your vehicle. It is an important part of the transmission of your audi a3 keys, as it transmits information to the ECU about how fast or slow the engine of the car is turning. This sensor could cause the transmission to malfunction and other components of the car to be affected.

The G5 engine sensor is located at the outskirts of the transmission, just above the flywheel ring. It transmits signals via gray wire to ECU pin T55/49. The ECU utilizes this signal to regulate the amount of fuel and boost, and keys also timig. It also transmits it to the G5 Tachometer in instrument cluster. You can check for sensor failure by examining the continuity of the sensor to the tachometer. Additionally, you can examine the continuity between pins T55/49 of the ECU and pin T6a/1 of the instrument cluster (trace [79]) and http://www.nrs-ndc.info/freecgi/EasyBBS/index.cgi?bid=2&popup=1&desc->http://talsi.pilseta24.lv/linkredirect/%3Flink=https%3A%2F%2Fpushkincc.org%2Fbbs%2Fboard.php%3Fbo_table%3Dfree%26wr_id%3D2577&referer=talsi.pilseta24.lv%2Fzina%3Fslug%3Deccal-briketes-un-apkures-granulas-ar-lielisku-kvalitati-pievilcigu-cenu-videi-draudzigs-un-izd-8c175fc171&additional_params=%7B%22company_orig_id%22%3A%22291020%22%2C%22object_country_id%22%3A%22lv%22%2C%22referer_layout_type%22%3A%22SR%22%2C%22bannerinfo%22%3A%22%7B%5C%22key%5C%22%3A%5C%22%5C%5C%5C%22Talsu+riepas%5C%5C%5C%22%2C+autoserviss%7C2021-05-21%7C2022-05-20%7Ctalsi+p24+lielais+baneris%7Chttps%3A%5C%5C%5C%2F%5C%5C%5C%2Ftalsuriepas.lv%5C%5C%5C%2F%7C%7Cupload%5C%5C%5C%2F291020%5C%5C%5C%2Fbaners%5C%5C%5C%2F15_talsurie_1050x80_k.gif%7Clva%7C291020%7C980%7C90%7C%7C0%7C0%7C%7C0%7C0%7C%5C%22%2C%5C%22doc_count%5C%22%3A1%2C%5C%22key0%5C%22%3A%5C%22%5C%5C%5C%22Talsu+riepas%5C%5C%5C%22%2C+autoserviss%5C%22%2C%5C%22key1%5C%22%3A%5C%222021-05-21%5C%22%2C%5C%22key2%5C%22%3A%5C%222022-05-20%5C%22%2C%5C%22key3%5C%22%3A%5C%22talsi+p24+lielais+baneris%5C%22%2C%5C%22key4%5C%22%3A%5C%22https%3A%5C%5C%5C%2F%5C%5C%5C%2Ftalsuriepas.lv%5C%5C%5C%2F%5C%22%2C%5C%22key5%5C%22%3A%5C%22%5C%22%2C%5C%22key6%5C%22%3A%5C%22upload%5C%5C%5C%2F291020%5C%5C%5C%2Fbaners%5C%5C%5C%2F15_talsurie_1050x80_k.gif%5C%22%2C%5C%22key7%5C%22%3A%5C%22lva%5C%22%2C%5C%22key8%5C%22%3A%5C%22291020%5C%22%2C%5C%22key9%5C%22%3A%5C%22980%5C%22%2C%5C%22key10%5C%22%3A%5C%2290%5C%22%2C%5C%22key11%5C%22%3A%5C%22%5C%22%2C%5C%22key12%5C%22%3A%5C%220%5C%22%2C%5C%22key13%5C%22%3A%5C%220%5C%22%2C%5C%22key14%5C%22%3A%5C%22%5C%22%2C%5C%22key15%5C%22%3A%5C%220%5C%22%2C%5C%22key16%5C%22%3A%5C%220%5C%22%2C%5C%22key17%5C%22%3A%5C%22%5C%22%7D%22%7D&control=f1427842db246885719585c9a034ef46 between pin T6a/1 and pin T26a/12. There should be the resistance to be around 1000 ohms between these points. This is a typical component across the audi tt key case 80, 100 200, UrS and RS2 range from 1985 MC until the 1997 UrS AAN and 1995 RS2 ADU. Good parts could be found in wrecking yards.